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Lieut. Commander FRANK LYON, U. S. Navy 

AND ^ 

Lieut. Commander A. W. HINDS, U. S. Navy 


Lieutenants W. P. BEEHLER and JOHN S. BARLEON, U. S. Navy 

Of the Department of Marine Engineering and Naval Construction, 

U. S. Naval Academy^ under the supervision of the 

Head of the Department 



Of the Department of Marine Engineering and Naval Construction 
U. 5*. Naval Academy, under the supervision of the 
Head of the Department 




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Copyright, 1912, by 


Sbc. and Trbas. U. S. Naval Institute 

Copyright, 191 S> by 


Sec. and Trbas. U. S. Naval Institute 

Annapolis, Mo. 

Copyright, 1930, by 


Trustee for U. S. Naval Institute 

Annapolis, Md. 

BALTUfORB, MD., U. S. A. ' 

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The " Text-Book on Naval Boilers/' by the late Captain P. 0. 
Bieg, U. S. N., has been in continuous use at the United States Naval 
Academy for the instruction of midshipmen since 1903. This book 
was one of the best^ for its purpose, ever produced at the Academy. 
The advances in the last few years, however, both in the art of boiler 
construction and management and in the use of liquid fuel, made 
imperative either a very thorough revision of Bieg or a new text- 
book giving the latest information on the subject. It was unfortu- 
nate for the midshipmen and for the naval service that the death of 
Captain Bieg caused the work of revision of the boiler text-book to 
fall on the shoulders of others. 

Early in the fall of 1910, at the request of the head of Depart- 
ment of Marine Engineering and Naval Construction, United 
States Naval Academy, the revision of Bieg was undertaken by 
Liieutenant Commander Prank Lyon, United States Navy, who 
was later joined in the work by Lieutenant Commander A. W. 
Hinds, United States Navy. 

As the revision progressed it was foimd that, while about one- 
fourth of the old text could be used, the rearrangement and different 
methods of handling the chapters would make the new edition very 
different in appearance and in contents from the book under re- 
vision. Por the above reasons, and due to the fact that some of the 
theories herein advanced may be disputed, it was decided by the 
revisers to accept the responsibility and publish the new book under 
their own names. This decision was referred to and concurred in 
by the Board of Control of the United States Naval Institute, the 
owner of the copyrights of the old book. 

The chapter on " Corrosion '' is the result of studies and experi- 
ments conducted by Lieutenant Commander Lyon during 1909, 1910 
and 1911. 

Sincere thanks are extended to Rear Admiral H. I. Cone, Engi- 
neer-in-Chief , United States Navy, and to his assistants, as well as 
to the manufacturers of the various types of boilers, fittings and 
accessories, for their uniform courtesy and valuable help. 

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4 Pbbfaob 

Grateful acknowledgment is made to the American Society of 
Naval Engineers^ and to Commander 17. T. Holmes, United States 
Navy, author of " Experimental Engineering/' for their generosity 
in allowing the use of both subject matter and cuts. 

Thanks are due to Commander M. E. Beed, United States Navy, 
head of the School of Marine Engineering, and to the students at 
that school for assistance given by criticising the manuscript before 
sending it to print. 

Pkank Lyon, 
A. W. Hinds, 

Lieut. Commanders, U. 8. Navy. 
United Statbs Naval Aoadbict, 
Annapoub, Md., Januabt, 1912. 

In the preparation of this book many other text-books and publi- 
cations have been consulted, among which are : 

Text-Book on Naval Boilers. P. C. Bieg. 

Steam Boiler Economy. Kent. 

Journal of the American Society of Naval Engineers. 

Machinery Specifications for U. S. Naval Vessels. 

Annual Report of the Chief of the Bureau of Steam Engineering. 

Journal of the American Society of Mechanical Engineers. 

Report of the Liquid Fuel Board. 

Marine Boiler Management and Construction. C. E. Stromeyer. 

Steam Boilers. C. H. Peabody and E. P. Miller. 

Marine Boilers. L. E. Bertin: L. B. Robertson's edition and 

Corrosion and Preservation of Iron and Steel. Cushman and 

Marine Steam by the Babcock & Wilcox Co. 

Steam Boiler. Powler. 

Power and the Engineer. 


Jones' Physical Chemistry. 

Circulars of Makers of Boiler Fittings and Accessories. 

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The work of revision of the excellent book on Marine and Naval 
Boilers, by Lieutenant Commanders Prank Lyons and A. W. Hinds, 
was imdertaken at the request of the XJ. S. Naval Institute, because 
the original edition was sold out and it was deemed advisable to 
cake advantage of the opportunity to bring the book up to date in 
every respect. The largest part of the work of revision consisted in 
the elimination of those types of boilers and accessories which have 
become obsolete, and the substitution of the latest designs and types 
installed in the U. S. Navy. 

As this book is intended primarily for the use bf midshipmen 
at the Naval Academy, a large part of it is necessarily devoted to 
details of construction, to the exclusion of the theory of boiler 
design. The theory of heat transfer, while of the utmost importance 
in the intelligent operation and management of boilers, is treated 
in a very general way because of lack of space, and on account of 
the omission of the study of technical thermodynamics from the 
curriculum. The discussion of combustion is also necessarily brief 
for the same reasons. 

The chapter on " Corrosion *^ as originally written by Commander 
Lyon was foimd to be too involved for the use of midshipmen, and 
it was considered necessary to omit most of the theory of corrosion 
and to substitute therefor a short discussion of experimental results, 
and of the practical methods of preventing corrosion. The elimina- 
tion of the theory does not indicate that a knowledge of such theory 
is undesirable and for a thorough knowledge of this subject the 
student is referred to the many good treatises recently published. 

The revisers desire to express their sincere thanks to Lieutenant 
O. S. Bryan, IJ. S. N., for assistance in the preparation of the 
chapter on " Corrosion *'; to the officers of the Bureau of Steam En- 
gineering, Navy Department, for their kind assistance in furnishing 
information and blue prints; to the J. A. S. N. E. for the use of 
subject matter and of the plate of "Temperature — Viscosity 
Curves"; to Mr. P. .H. Rittenour for the tracings used in making 

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6 Pbbfaob to Second Edition 

some of the plates, and to the several manufacturers who furnished 
subject matter and blue prints for some of the cuts and plates. 

Special thanks are due to Commander H. B. Price, U, S. Navy, 
Head of the Department of M. E. & N. C, for his helpful sugges- 
tions and criticisms, while supervising the work of revision. 
W. P. Beehleb, 

Lieutenant, U. S. Navy, . 
John S. Bableon, 

Lieutenant (J. 0.), U. 8. Navy. 


The revision of this book was undertaken at the request of the 
TJ. S. Naval Institute. The second edition having been sold out, it 
was deemed advisable to take advantage of the opportunity presented 
to revise the book before printing another edition. 

This revision consists primarily in eliminating obsolete types and 
substituting more modern ones in their place. A few corrections 
have been made. 

The reviser desires to express his thanks to the officers and instruc- 
tors of the Department of Marine Engineering and Naval Construc- 
tion for their assistance with helpful suggestions and criticisms. 

W. L. Friedell, 

Commander, U, S, Navy. 

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I. DKrmmoNB, Fbinoifleb AND TTPsa 9 


III. Watbb-Tubb Boilebs 42 

IV. BonJEB Fittings 78 


VI. Hbat, Hbat Tranbfeb and Evaporation 166 

VII. Combustion 181 


IX. Coal 202 

X. Liquid Fukl 220 

XI. FiBiNO 247 

XII. Dbaft, Natubal and Fobged 267 

XIII. CoBBOSiON AND Wateb Tbeatmbnt 280 

XIV. Cabb and Management or Boilebs 801 

XV. Boileb Tests 822 

Appendix and Tables 339 

Index 388 

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A steam boiler is a vessel in which, by the ageoicy pf heaid^ved 
from the combustion of fuel, water is converted into steamy abdio 
which the steam is raised to the temperature and pressure required 
for use as the prime mover of machinery. A marine steam boilei 
is one adapted for use on board ships.* 

Goal is the fuel in most general use in marine boilers. 

Many marine boilers are now fitted to burn either liquid fuel 
alone, coal and liquid fuel at the same time or coal or liquid fuel 
separately in the same furnace. In the United States Navy all new 
battleships have their boilers fitted to bum either coal or liquid fuel 
alone or both at the same time; all new destroyers are fitted to burn 
liquid fuel only. The latest battleships contracted for are to bum 
liquid fuel only. 

The energy released by the combustion of the fuel is transferred 
through the heating surfaces to the water in the boiler, converting it 
into steam, and raising the steam and water to the temperature that 
gives the required pressure. The steam is then led from the boiler 
through pipes and valves to the various engines, where its heat is 
converted into mechanical energy for use direct, or for conversion 
into the electrical, hydraulic or pneumatic energies, which are now 
used to a great extent in all classes of naval vessels. 

Heating surfaces are all the metallic surfaces that transmit heat 
from the flames or gases of combustion to the water. They consist 
of the surfaces in contact with flame or gases of combustion, on one 
side, and of all the water-containing parts of the boiler, on the 
other, from the level of the grate bars to the water line in the steam 
drum. The superheating surfaces are all those surfaces in contact 
with flame or gases of combustion, on one side, and steam on the 

In all cases of measuring the heating or superheating surfaces of 
a boiler, those to be measured are the surfaces in contact with the 
flame or gases of combustion, and not those in contact with the 

* " Kent's Steam Boiler Economy." 

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10 Mabikb and Natal Boilsbs 

water and steam^ as^ for instance^ the inside diameter of a fire tube 
and the outside diameter of a water tube. 

The general requirements of a good marine boiler are that it 
should be designed so that it may have : 

1. The maximum heating surface in proportion to its weight. 
2^ T]if ^i^imum strength with minimum thickness and weight 
•of maierial.' '• * 

;'|:9.'trhe h^imum strength due to its. form without artificial 
*8ilpfbrf/ ' " 

4. The maximum resistance of its component materials to cor- 
rosion and erosion. 

5. The maximum circulation of its contained water. 

6. The maximum circulation of the hot gases of combustion in 
contact with its heating surfaces. 

7. The maximum transference of heat per unit of the heating 

8. The minimum weight in proportion to steaming power. 

9. The minimum of fuel consumed per eflfective horse-power. 

10. The minimum of water delivered with the steam. 

11. The minimum of heat delivered to the atmosphere. 

Marine boilers are divided into two general classes: (1) Fire- 
tube boUers, (2) waier-iube boilers. 

Fire-Tube Boilers. — ^The boilers of this class have a relatively 
large quantity of water contained in a closed tank or shell. This 
shdl also encloses the furnace^ in which the fuel is burnt; the com- 
bustion chamber^ in which the volatile combustible matter is con- 
sumed; and the tubes^ through which the heated gases of combustion 
are passed on their way from the combustion chamber to the uptake. 
Different authorities use various names for this class of boilers^ such 
as Scotch, shell, tank, tubular or fire-tube boilers; the name used 
throughout this book will be fire-tube boilers, for the reason that 
the hot gases of combustion pass through the tubes. The tubes in 
all cases are surrounded by the water contained in the shell. 

A fire-tube boiler may be (1) a return fire-tube boiler, or (2) a 
direct fire-tube boiler. 

(1) The return fire-tube boiler is one in which the gases of 
combustion pass to the uptakes from the upper part of the combus- 
tion chamber^ through tubes^ over the furnace in which the fuel is 
consumed. They may be either single-ended or double-ended ; that 

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Definitions^ Principles and Types 11 

is, they may have ftirnaces^ combustion chambers and tubes in one 
end only or in both ends. . 

(2) The direct firertube boiler is one in which the g4^e8 of com- 
bustion pass from the combustion chamber to the uptakes through 
tubes placed in the end of the boiler opposite to that in which the 
furnace is placed. There are two types of direct fire-tube boilers— 
the gunboat l^pe and the locomotive type. 

In the i^nboat type the volatile combustible constituents of the 
fuel are consumed in a combustion chamber placed at the inner end 
of the furnace; in the locomotiye l^pe the gases are consumed in 
an enlarged space directly over and forming an integral part of the 

More detailed descriptions of fire-tube boilers will come in Chap- 
ter II. 

Water-Tube Boilers. — ^Boilers of this class have a relatively small 
quantity of water enclosed in drums, connected by tubes, around 
which the gases of combustion are passed on their way from the 
enclosed furnace, at the base of the boiler, to the uptake. These 
boilers are also called tubvlous boilers, but the name employed 
throughout this book will be water-tube boilers, for the reason tiiat 
the water to be heated passes through the tubes. 

Water-tube boilers are generally known by the names of their 

Clasiifloation of Water-Tube Boilers. — ^They are classified in sev- 
eral different ways— one with regard to size of the tubes, one with 
regard to whether the upper ends of the tubes enter the steam drum 
in the steam space or in the water space, and one with regard to 
steam and water circulation. 

Size of Water Tubes. — ^AU water-tube boilers are of either the 
large-iube or the small-tube l^pe; those having tubes 2"^ or larger, 
outside diameter, are of the large-tube type; those with tubes of 
less than 2," outside diameter are of the small-tube type. 

Small-tube boilers, which have a very large amount of heating 
surface made up of many small, thin tubes, are said to be of the 
express type. The Babcock & Wilcox boiler is the most familiar 
example of the large-tube type ; the Thomycroft, of the small-tube 
type; and the Normand, of the express type. 

Above-Water and Drowned-Tube Boiler8.-*Water-tube boilers 
in which the upper ends of the circulating tubes enter the steam 
space of the steam drum, are known as above-water or nonreversible 

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12 Marine and Natal Boilers 

cijcle boilers; non-reversible, as the steam and water can only flow 
one way. The best examples of these are the early Thomycroft and 
Mosher boilers. When the tubes enter the water space of the steam 
drum they are drowned-tube, or reversible-cycle boilers; reversible 
cycle, because the water and steam can flow either way. The best 
known examples of this type are the Yarrow, Normand, White- 
Forster and Stirling. The above-water type is now obsolete, but the 
drowned-tube boiler is in general use. 

Circulation. — Classed as to circulation, all water-tube boilers are 
of one of the following types : 

(a) Boilers with limited circulation, 

(b) Boilers with free circulation. 

(c) Boilers with accelerated circulation, 

(d) Boilers with forced circvJation, 

(a) Boilers with limited circulation have tubes of coil or ser- 
pentine form inclined to the horizontal; sometimes they have only a 
single tube of helical shape surrounding the furnace. There is no 
circulation except that necessary to replace the water evaporated. 
The water enters the tubes at the lower end and discharges from the 
other end as steam into the steam drum. There are no vertical legs 
by which the steam bubbles can escape freely into the drum; they 
must travel in the inclined tube through the stagnant water. 

(b) Boilers with free circulation comprise those in which the 
slightly inclined or nearly horizontal tubes extend between vertical 
flat-water spaces or headers at the front and back or on the sides, 
or those that have nearly horizontal Field tubes.* 

These tubes receive their water from one reservoir and discharge 
it into the other as steam, or as a mixture of steam and water. The 
water and steam both travel in the tubes and are free to rise at the 
vertical headers. 

(c) Boilers with accelerated circulation comprise those with 
horizontal drums or reservoirs placed at different heights connected 
by vertical or nearly vertical tubes ; and those having nearly vertical 
Field tubes. Boilers with accelerated circulation are characterized 
by the direction given to the water, which is as nearly vertical as pos- 
sible in its passage between the drums. Large down-comer tubes, 
or, in some cases, the rows of tubes away from the flre, return the 
water from the steam drum to the lower drums. Everything is ar- 
ranged to facilitate a continuous and general circulation. 

* A Field tube is a tube consisting of an inner or QirQ^lQting tub9 and 
an outer or generating tube. 

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(d) Boilers with forced circnlation comprise those in which 
circulation is stimulated by pumping feed water through the boiler. 
They are not used for naval purposes. 

Comparison of Fire-Tube and Water-Tube Boilers. — Aside from 
the material difference in construction of fire-tube and water-tube 
boilers, they each have their advantages and disadvantages for 
marine work. 

The advantages of the fire-tube boiler are : ( 1 ) Owing to the large 
volume of heated water in these boilers and the large steam space, 
they answer to fluctuations in speed with slight attention to fires ; 

(2) the furnace being enclosed in the shell, there is a smaller radia- 
tion loss from the furnace; (3) there are fewer joints to keep tight; 
(4) less attention is required to water-tending; (5) there is less 
danger from using salt or impure feed; (6) they are easier to ex- 
amine and clean. 

The advantages of the water-tube boiler are: (1) Less weight 
per unit of power generated ; (2) less boiler space per unit of power ; 

(3) ease by which they can be removed from or replaced in a ship; 

(4) less time and care required to get up steam; (5) less danger to 
life and to the ship from boiler explosion; (6) more units in power 
installation, so that one boiler out of order decreases total power to a 
less extent; (7) greater suitability with safety for high pressures; 
(8) greater ability to stand forcing; (9) less liability to leaks 
brought about by expansion and contraction. 

The following table gives the type of boiler now generally used 
for the several types of ships, with the pressures and kind of pro- 
pelling machinery usually employed in the U. S. Navy. 




water- tube. 

Type of ship. 

Small-tube J 
water-tube. 1 



Large cruisers. 

Auxiliary vessels. 


Small, fast cruisers. 


Battle cruiser. 


Recip. and turb. 

Recip. and turb. 
R«cip. and turb. 
Recip. and turb. 
Recip. and turb. 
Recip. and turb. 
Electric drive. 
Electric drive. 

Steam preisure Ibt. 
per aq. in. 

100 to 200. 
175 to 315. 

250 to 300. 

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Fire-tube boilers are not now being installed in any of the armed 
vessels of the U. S. Navy. When the fire-tube boilers installed in 
the older armed vessels need extensive repairs^ they are generally 
replaced by water-tube boilers. Some of the newer fleet colliers have 
water-tube and some fire-tube boilers. The Neptune and Cyclops 
have three double-ended return fire-tube boilers and one single- 
ended return fire-tube boiler; the single-ended boiler is intended 
mainly for use in port. The Vulcan has four single-ended return 
fire-tube boilers. The colliers Prometheus and Vestal, built at 
navy yards^ are each fitted with six water-tube boilers. There are 
only two vessels^ the Castine and the Machias, fitted with locomo- 
tive boilers of the direct-tube type, and only a few ships have the 
gunboat direct-tube type. 

In a few more years all armed vessels that now have fire-tube 
boilers will have had them replaced by water-tube boilers or the 
vessels will have been scrapped. 

Double-Ended fietum Kre-Tube Boilers. — Plate I shows two 
views of a double-ended return fire-tube boiler. Fig. 1 is a front 
elevation and Fig. 2 a side elevation with the right half in section 
through the center of the lower right furnace. The boiler is cylin- 
drical, as may be seen from this plate. 

The cylinder, closed at each end by a flat head, is called the shell. 
Built inside of the shell at each end are four furnaces F, each fur- 
nace having its own combustion chamber A, and nest of tubes T. 
The fuel is placed through furnace doors Q on grates 0, the gases 
of combustion pass from F into A, through T out of the boiler into 
front connection C; through the uptake U, through breeching * (not 
shown), through smoke-pipe (not shown) to the atmosphere. 

When the boiler is ready for steaming, the shell is fllled with fresh 
water to about three indies above the top of A'; the water then 

* The breeching connects the uptakes of several boilers to the commoo 

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FiBE-TuBB Boilers 15 

completely surrounds all parts of the boiler in contact with the fire 
or gases of combustion in i'', il and T, The space left above the 
water, called the steam space, collects and contains the steam as it is 
formed when combustion is taking place in P. Near the top of this 
space, steam may be drawn for use through slots in the dry pipe D, 
which connects with the stop-valve W, through an opening cut in 
the boiler head. By means of W the supply of steam for use can be 

The two furnaces on the right of Plate I, Fig. 1, are shown with 
the furnace front R, furnace door Q, and ash-pit door P removed. 
Fuel is placed on the grate through door Q; and the air necessary 
for combustion of its volatile combustible gases is admitted over the 
fire through small holes in R and Q; and that necessary for the com- 
bustion of its non-volatile matter, under the fire through semi-circu- 
lar openings left by removing P. The air finds its way up through 
the fuel. 

The grate consists of a series of grate bars supported on bearer 
bars, and it divides the corrugated furnace proper into the furnace 
P and the ash pit P'. The lower part of P' is covered with an ash 
pan P". 5 is a slicing door in Q for working the fire without open^ 
ing the door. J3 is a fire-brick bridge wall built on an iron frame; 
it makes a back wall for the fire, and slightly reduces the outlet for 
the gases of combustion as they pass from P to A. 

C and U are secured to the outside of the boiler, and are, there- 
fore, not integral parts of it. Access to the interior of and U, 
and to the front ends of the tubes T, is obtained through the connec- 
tion doors V, three of which are shown in place; the fourth one is 
removed from its hinges and shows the front ends of the tubes. 8D 
are soot doors in the bottom of C, and there are three sliding damp- 
ers above V for regulating the draft and rate of combustion. The 
steam pressure, above the atmospheric pressure, inside the shell, is 
shown by the steam gage SO, and any excess of pressure above that 
at which the safety valves 8f are set is relieved by them. The 
water-gage glasses WO and the gage cocks 00 are used to indicate 
the water level in the shell. K and L are small valves on the water 
columns connecting WO to the steam and water spaces of the shell. 
The supply of water to the shell is regulated by means of the feed 
check-valve and feed stop-valve at E; a pipe connects this with the 
feed pimips. Access to tiie interior of the shell is obtained through 
the manholes M'; three of these are shown closed by the manhole 

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16 Mabinb and Naval Boilers 

plates M. H is the surface blow-valve connected to the water in the 
shell by the internal pipe and scum pan 8P. A pipe leading from 
H overboard is connected to the bottom blow-valve J. I is the 
hydrokineter valve for aiding water circulation when getting up 
steam ; there is one at each end of the boiler. 

Z, at the top of the shell, is the air cock, and DC, at the bottom, 
is the drain cock. Y is the dynamo stop-valve. 

All flat surfaces exposed to pressure must be stayed, braced or 
otherwise strengthened at regular intervals. The combustion cham- 
bers A are practically rectangular boxes of thinner plates than the 
boiler heads, and need much staying and stiffening. The flat heads 
are tied to each other by the braces 0, of which there are four hori- 
zontal rows above the tubes and three surrounding the lower 
manholes. Similar braces, but shorter, tie the remaining flat and 
unbraced parts of the heads to the unbraced parts of the front com- 
bustion-chamber plates. The back and side plates of these chambers 
are stayed to those of the adjoining ones, or to the shell of the boiler, 
by screwed stay bolts; their flat bottoms are stiffened by three angle 
irons and their flat tops by the girders A'. 

The front plate of the combustion chamber is called the back tube 
sheet; the middle plate of the boiler head is called the front tube 
sheet. These tube sheets are tied to each other by the ordinary 
tubes expanded into each plate, and by the heavier stay tubes 
screwed into each plate. 

The boilers are supported by the saddles N built up from the hull 
of the ship, and are placed in water-tight compartments called 
boiler compartments. 

The saddles are generally secured to the shell by means of brackets 
which are riveted to the shell and bolted to the saddles. 

The number of boilers in each compartment depends upon their 
kind and size, and the size of the ship. 

The fire-room is the space left in each compartment at the furnace 
ends of the boiler, and must be long enough to enable proper hand- 
ling of firing tools. On board ship, the boiler compartments are 
called fire-rooms. 

The boilers may be placed either fore and aft or athwartships. 
Communication between boiler compartments is by fire-room pas- 
sages or doors; the doors are water-tight. 

The steam spaces of the boilers are connected through a system 
of pipes and valves to each other and to the various engines. 

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FiBB-TuBB Boilers 17 

The uptakes of a certain nest or number of boilers join in the 
breeching on top of which is set the smoke-pipe. 

The rectangle enclosing the outside limits of the grate is called 
the grate surface. 

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Fihb-Tdbb Boilbrs 


> § B 

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22 Mabine and Naval Boilbbs 

The principal component parts of fire-tube boilers and the 
methods of securing them together are as follows : 

The shell plates are of class B boiler-plate steeL* The circum- 
ferential seams, where secured to boiler heads, are double riveted. 
The circmnferential seams of the middle-shell plate are treble 
riveted, as may be seen by an inspection of Plate I. The longi- 
tudinal seams are double butt strapped and treble riveted, as shown 
in Fig. 4. The right-hand figure represents a section on X'Y', 
Fig. 2, Plate I, the section passing through the two rivets shown 
full in Fig. 4. 

/-^ /— V r^ -Ay. . _^ ^5 __ __ -~J\ r^ /"^ c\. 

■: l/^'/y:|^X I^^^XnI N 

Fig. 4. — ^Double Butt Strap Longitudinal Seam. 

The inner butt strap B' is rectangular, like the rest of the butt 
straps, and needs no special fitting at the ends. The outer butt 
strap B is planed down on each side to form a lip which passes 
under the outer courses. The latter are chipped and filed, or planed 
before bending, on the inside to suit the lips of the butt and make 
smooth joints. Enough clearance is left at A, A for calking. 

Fig. 4a represents a section on X''Y''y Fig. 2, Plate I. The outer 

Z o ¥^tr He ad or 
Furnace Shee t, 

M/eld/e Course 
Ircum feren t/al Scam. 
Inside Buff Stra, 

Outs /de-Burt Strap 
£nd Course, 

Outs ide Butt Strm/». 
Outside or£nd Course 

Fig. 4i. 

strap, B, is rectangular, except for the removed comers at the ends. 
The inner strap, B\ is planed down at the ends to fit properly shaped 
recesses in the middle course edge and the furnace sheet fiange, as 
shown. SuflBcient clearance is left at B for calking. 

* Class B boiler-plate steel is specified to have: (a) A tensile strength 
of 68,000 to 66,000 pounds per square inch; (b) an elastic limit of one- 
half (a) ; (c) an elongation of 26 per cent in a length of 8 inches; and 
(d) a maximum limit of .036 per cent of phosphorus and sulphur. 

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Hydraulic riveting is required wherever it can be used; where 
ihe riveting must be done by hand, the holes must be coned and 
conical rivets used. All of tiie joints in the shell can be made by 
machine-riveting, and the holes are, therefore, drilled as shown on 
ihe left in Fig. 5 ; those for hand riveting are shown on the right. 

Fig. 6. — ^Methods of Riveting. 

All holes are drilled ^^ larger than the rivet. With machine- 
riveting, the end of the rivet is formed either into a button point 
(dotted lines), or into a truncated cone. With hand-riveting, the 
conical point is generally formed. 

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24 Marikb and Naval Boilers 

Head Sheets. — ^The furnace manhole^ handhole and stay rod open- 
ings of the lower head sheet or furnace plate are shown in Pig. 6. 

Fio. 6. — Lower Head or Furnace Sheet 
The middle head sheet or front tube sheet is shown in Fig. 7. 

Pig. 7. — ^Tube Sheet 

The shape of the top head sheet may be seen from an inspection 
of Pig. 1, p. 18. It has stay openings, manhole and boiler fitting 
openings as necessary. 

In both the figures, the outer broken line shows the original size 
of the plate from which the finished sheet was made, and the inner 
broken line shows the developed surface of the finished sheet. 

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The methods of flanging the head sheets and connecting them to 
the shell plates are shown in Fig. 8. The head sheets are made with 

Fio. 8. — Flanging Heads to Shell. 

the flanges turned inward, as on the right, or outward, as on the left. 
The method shown on the right is the general practice. 

Fig. 9 shows the method of flanging and riveting the head sheets 

Fio. 9.— Riveting Head Sheets. 
Fig. 10, on the left, shows the method of securing the combustion- 

OiUL SHEET olDE ^sioc shcet 

Fio. 10. — ^Riveting Combustion-Chamber Sheets. 

chamber sheets together; and, on the right, the method of securing 
the combustion-chamber sheets to inner end of the furnace. 

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26 Mabinb and Naval Boilebs 

Fig. 11 shows the method of bracing the fiat top of combustion 
chamber by means of girders. 

Fig. 11. — Girders for Bracing Top of Flat Combustion Chamber. 

Fig. 12 shows the same by means of angle-bar girders with curved 
top plates ; also the method of bracing the fiat back sheet of combus- 
tion chamber to the back head sheet of single-ended return fire-tube 

Fig. 12. — Girders for Bracing Top of Curved Combustion-Chamber Sheet 

boilers, or of tying together the two back combustion-chamber 
sheets, in double-ended return fire-tube boilers, by means of screw 

Fio. 18. — Screw Stay Bolt 

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Fig. 13 shows the screwed stay bolt bracing the back combustion- 
chamber sheet; the same method is used to brace the flat side com- 
bustion-chamber plate to the shell of the boiler. 

Fig. 14 shows the method of fitting through stays at the head 
sheets. The upper sketch shows the method of fitting washers 
where the stay passes through the sheet at right angles to it; the 
lower one shows the method where the stay goes through the sheet 

Fia. 14. 

Fio. 16. 

Braces and Stays. 

at an angle other than a right angle. Fig. 15 shows the method of 
connecting the stays to front combustion-chamber sheet. 

Furnace. — Although the cylindrical furnace is less efficient than 
the rectangular one, chiefly on account of the limited space 
above and below the grate, yet it is the only one used in fire-tube 
boilers. It is easier to manufacture; it can be and is made with 
only two joints which need be kept tight, one at each end ; and, as it 
requires no stays, the interior of the boiler, around the furnaces, 
is accessible for cleaning. These advantages outweigh its one dis- 

The older form consists of two or three short plain cylinders, 
riveted to each other by flanges turned on the ends, with a stiffening 

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Mabinb and Naval Boilebs 

ring between the flanges. This joint is called an A damson ring and 
is shown at il in Fig. 16. For pressures^ say, above 80 pounds, the 
plain furnace would not be strong enough without making the plates 
too thick. The necessity for increased strength led to the adoption 
of the Fox corrugated furnace, made in one length, as shown at B. 
Later forms of tiiis type are shown by the Purves ribbed flue 2>« 
and the more recent Morison suspension furnace C, which is a com- 
bination of the Fox and Purves. 

The Fox furnace B is of equal thickness throughout, and has nar- 
row corrugations, spaced about 6" between crests or tops, and 

Fig. 16. — ^Furnaces. 

projecting equally above and below the mean diameter of the 
furnace. The narrow cavity formed on the water side by the 
inward groove, 1^" deep, gives good opportunity for an accumida- 
tion of deposits, which is rather diSicidt to remove properly. As 
these cavities are nearer the fire, the material, if not clean on the 
water side, becomes unduly heated and frequently cracks at the bend. 
This defect is overcome in the Purves furnace D, which has the 
strengthening ribs in the water space, and, therefore, offers no 
cavities. But the fiat surfaces, 9'' between the ribs, being the 
weaker, are the first to sag or collapse. Owing to the stiffening 
rib, the thickness of the furnace, and, therefore, its strength, is not 
the same throughout. In the Morison furnace G the corrugated form 
is retained for strength, but, by making the outward corrugations 
shorter and utilizing them as stiffeners, the inward corrugation, 
suspended between them, can be made longer, 8^^, the small cavities 
being thus avoided. The thickness of the furnace is uniform. 

All furnaces are made of steel, the plate being usually •^'^ thick, 
with slight variations depending on the quality of the material and 
the boiler pressure. The least internal diameter varies from about 

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FiRE-TuBB Boilers 29 

36" to 42". T}ie corrugations of adjacent furnaces are made to 

Fig. .17 shows a finished suspension furnace with small flanges, 
as fitted for separate combustion chambers. This furnace is a re- 
movable one, the diameter of the straight part at the back being 
less than that of the corrugations. The diameter of the straight 
part at the front end is made slightly larger than that of the cor- 
rugations, to facilitate the entry of the flue into the furnace hole 
in the lowor sheet of the boiler. 

Flo. 17. — Suspension Furnace. 

Tubes. — ^These are always straight and are of two kinds, ordinary 
and stay tuies, the latter being the heavier or thicker, but both hav- 
ing the same external diameter. The material of tubes is seamless 
cold-drawn steel. 

Ordinary Tubes. — These, which are the more numerous in a 
boiler, are now made from No. 9 to 12 B. W. G. (.148" to .109") 
thick, with the front ends swelled to a slightly larger external 
diameter, from ^" to i", to facilitate their entry and removal. 
The holes in the tube sheets are drilled slightly larger than the 
tubes, 80 that the latter can be pushed into place by very slight 
pressure, and the tube holes are rounded at edges to prevent cutting 
the tubes when being expanded. Both ends of the tubes are then 
made tight by an expander* The back or combustion-chamber end 
of the tube is then beaded over, as shown, to protect the end from 
the fire and to add a little to the holding power. 

Stay Tubes. — These, as their name shows, act as stays between 
the two tube sheets, and are, therefore, secured in a different man- 
ner. They are usually No. 6 B. W. G. (.203") thick, and are re- 

* The details of the expander and the method of its use are explained 
In the chapter on " Accessories." 

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Mabinb and Naval Boilers 

inf orced at both ends to an external diameter usually i" greater 
than the rest of the tube, the bore of the tube remaining uniform 
from end to end. The front ends are then swelled an additional 
i", 80 that the external diameter at this end is i" greater than the 
body of the tube. Both ends are then threaded, usually parallel, 
but sometimes tapered at the front end. The tube is screwed into the 
threaded holes in the tube sheets until a tight joint is made in the 
front sheet. The back end is then expanded and beaded over, and 
this end and the adjacent sheets are further protected by a cast- 
iron ferrule, as shown. These ferrules, which are sometimes also 
used in the back ends of the ordinary tubes, have an internal diam- 
eter of from li" to 1}", and are simply driven into place by slight 

Fig. 18.— Ordinary and Stay Tubes. 

hammering. The round cap projects over the beaded tube end 
and, by conducting the heat to a part of the tube surrounded by 
water, protects the tube end and joint from the direct action of the 
hot gases. When the caps are burned off, the ferrules can be renewed 
easily. When cleaning tubes with brushes, these ferrules are liable 
to be pushed out. Ordinary tubes, when much reduced in thickness 
by frequent expanding, may be strengthened for a time by straight 
ferrules expanded in the ends. 

The holes in the tube sheets are drilled in vertical and horizontal 
rows, the spacing between vertical rows being the greater. 

This arrangement gives better opportunity for cleaning the tubes 
on the water side and improves the circulation. While more tubes 
could be put into a given tube sheet by staggering them, i. e,, 
putting them in zigzag, this arrangement interferes entirely with 
the cleaning and does not improve the circulation. 

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Water-Tubb Boilbks 47 

two sets of flame plates and baffle plate J J and 11 is the second 
pass, and that between the flame plates near the front and the front 
headers is the third pass. Thus, the gases pass np through the 
flrst, down through the second and up again and out through the 
third pass. 

This boiler is fitted for burning coal ; for burning coal and liquid 
fuel, either singly or in conjunction; and lends itself very readily 
to being fitted for burning liquid fuel, on account of its high com- 
bustion space and large furnace volume, as shown in Plate Illb. 
When the boilers are fitted to burn either coal or oil or both, the 
oil burners are placed between the furnace doors. When burning 
oil only, the grate bars are removed and the ash pan is covered with 
bricks or with cinders and ashes. 

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48 Mabine and I4a7al Boilers 

Fig. 25 shows the Babcock and Wilcox boiler complete, showing 
the cleaning and dusting doors on the sides and the system of lag- 
ging the casing of the boiler with non-conducting material. The 
cleaning doors have smaller doors in them, for inspection as to the 

Fio. 25. — Babcock and WUcox Boiler. 

condition of the combustion in the different passes and as to clean- 
liness of the outside of the tubes. Steam or compressed-air nozzles 
are entered through the smaller doors for tube-cleaning when under 
way. Bottom blow connections are fitted at the side of the bottom 
of each front comer upright ; the other fittings are secured to pads 
on the drum or drum heads. 

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Steftm Ihmn Heads. — Fig. 26 shows the form of the heads for the 
Bteam drums. They are made of one piece with manholes and open- 
ings for other boiler fittings^ and are bumped into shape. 

Fis. 26. — Head of Steam Drum. 

Superheater. — The superheater when fitted, is as shown in Pig. 
27. It consists of two steel boxes, A and B, lying across and on top 

Fig. 27. — Superheater. 

of the boiler at the back; these boxes are connected to each other by 
a series of pairs of 2" steel tubes. 

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60 Marine and Naval Boilbes 

The upper box A is longer^ as the pipes for the entering and 
the superheated steam are connected to its ends. The tubes extend 
forward from the boxes about two-thirds of the distance between 
the steam drum and the boxes; the rear casing of the uptake comes 
down at the bend of the tubes. The boxes are secured to the rear 
headers and to each other by channel irons and braces. 

The interior of the upper box is divided into three lengths by 
two diaphragms, and the lower one into two lengths by one dia- 
phragm. The steam from the boilers, which enters at one end of 
the upper box, is thus forced to travel down and up and through 

Fig. 28. — Superheater, Back View. 

the tubes four times before it leaves the upper box at the other 
end, thus taking up the heat of the gases of combustion to the best 
advantage. Fig. 28 shows the subdivision of A and B and coursp 
of steam through superheater. 

The bafHes plates among the generating tubes are fitted differently 
from the usual arrangement, owing to the presence of the super- 
heater. There are two bafHes, as usual, but the rear one extends 
from the lower tubes of the suporhoater down to the top of the 

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Watbk-Tubb Boileks 51 

4" tubes over the fire. The front baffle extends down from the 
rear casing of the uptake only part way. The gases enter among the 
generating tubes at the back of the furnace^ rise into the superheater^ 
thence down between the two baffles, and up into the uptake near 
the front of the boiler, as shown by the arrows. 

The boxes are fitted with handhole plates giving access to four 
tubes, as in the headers. The tubes are expanded into the boxes and 
are flared after expanding. Dusting doors are fitted in the sides of 
the superheater casing. The heating surface of each' superheater 
is about 10^ of that of the boiler. 

Details of Construction. 

As the construction of this boiler is very simple, not much need 
be said in explanation of it. 

The Brum. — This is made of steel; the shell is made of two 
plates, with double butt straps. One of these plates extends around 
one-fourth, and the other three-fourths, of the circumference, the 
smaUer plate being in the lower back quadrant of the shell. The 
holes for the return tubes and for the connecting tubes to the front 
headers are drilled in the center-line of the butt straps. The tubes 
are expanded into the straps only, the holes in the shell plates being 
slightly larger. The drum is built under the same general specifi- 
cations as are fire-tube boilers. The heads are formed in single 
heat, by hydraulic presses, to a spherical surface, the radius of 
which is equal to the diameter of tiie shell. 

The manhole is fianged in the shell plate or head, with a stiffen- 
ing ring of sufficient thickness to form, with the edge of the plate, 
a seat V wide for the gasket. Fig. 26 shows a drum head with man- 
hole. The plates for the latter are of compressed steel ll'^ by Ih''^ 
faced to fit the oval hole. 

Headers. — The corrugated headers are formed into seamless- 
drawn tubes from square blanks of open-hearth sheet steel, ^^ 
thick. In a single heat, they are squared on a mandrel and cor- 
rugated on both sides by hydraulic presses; and, after annealing, 
they pass to multiple tools that bore and face the handholes, other 
multiple drills being used for boring the tube holes. By the use of 
this form of header or manifold for connecting the tube ends, a 
perfectly fiat tube sheet is obtained, which requires no stays or 
braces, as the sides of the header are sufficient for that purpose for 

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62 Marine and Naval Boilers 

any steam pressure required. In the latest design of rear header, 
that portion of the extension which forms the tube sheet for the 
return tube is pressed out or pocketed, so that the tube seat will be 
at right angles to the axis of the tube. The ends of the headers are 
closed by }" steel plates welded into place. 

Fio. 29. — Headers. 

The header is shown in Fig. 29. The tubes are arranged in 
clusters of four, each cluster being opposite a handbole 5" square. 
It will be seen that the tubes may be examined, cleaned, or renewed 
without difficulty.. 

Overhauling the Boiler. — The tubes can be cleaned on the inside 
by straight brushes or, if necessary, by scrapers, or by steam or air 
turbines. The baffle over the furnace is likely to \rarp and need 
renewal after some time. 

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Watbr-Tubb Boilers 63 

Spare Parts and TooIb. — ^The tubes being straight and of com- 
mercial size, only the usual allowance need be carried. A few 
side boxes^ handhole plates^ dogs and gaskets complete the allow- 
ance of special parts necessary. Short and long nipples may be 
cut from the 4" tubes and annealed. 

Ordinary tube expanders of the proper sizes^ and an expander 
fitted to work from the farther end of the short connecting tubes, 
some metal tube plugs^ and an extractor should be on board. 

Benewing Defective Tubes. — ^A defective tube can be replaced 
by a new one as quickly as it can be plugged, and no more water is 
lost by the former process than by the latter. A good boilermaker, 
or machinist, can replace a tube in a very short space of time. 

Cleaning. — The main objection to boilers of this type, of which 
there are many in the United States Navy, is the expense in labor, 
time and material that is required to thoroughly clean them when 
cleaning becomes necessary. A new gasket for each handhole plate 
removed is generally required. Each handhole plate must be 
cleaned, and also the gasket seat in the header ; and, after cleaning, 
each handhole plate must be made tight. 

Renewing Flame Plates. — ^The flame plates of the baflfles among 
the generating tubes may work loose and fall down, on account of 
vibration of the boiler or bulging of the tubes. When the flame 
plates fall down, some of the gases of combustion take a shorter path 
to the uptake and there results a marked falling off in the efficiency 
of the boiler. The plates are renewed by laying them flat and 
passing them between the tubes until in the required position and 
then turning them upright on edge. They are grooved on each 
side to fit between the rows of tubes, and the grooves are chamfered 
on the opposite edges so that they may be more readily turned from 
the flat to the upright position. 

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54 Marine and Naval Boilers 

Securing Brick Linings to Furnaces. — ^In the oil-burning boiler^ 
the brick lining of the furnace must be firmly secured to prevent its 
jarring loose on account of vibration. There are several methods 
in use. Pig. 30 shows the method employed for the boiler in 
Plate Illb. 


Fig. 30.— Method of Securing Fire Brick. 

The Dyson Boiler. 

The Dyson Boiler, designed by liear Admiral C. W. Dyson. 
U. S. Navy, consists essentially of the cylindrical steam drum A, 
two water drums BB, tubes C, and superheater D, E, and F, Plate V. 

The ivater drcidaiion in this boiler is as follows: The feed 
water is forced into the steam drum A, and flows down to the water 
drums BB, through the tubes furtherest away from the fire: the 

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Watkr-Tubb Boilbbs fifi 

steam and water flow up to the steam drum through the hottest 
tubes. Steam then flows from A, through drypipe, stop valve, and 
steam pipe, to D, up through tubes E U) F, then out through drypipe 
to steam line. 

Furnace Oas Circulation. — The relative position of the super- 
heater tubes in the lanes among the generating tubes provide 
bafiling in wake of the uptake. This causes the gases in the lower 
part of the furnace to back completely through the lower half of 
the generating tubes instead of having a tendency to short circuit 
directly from the furnace up towards the uptake, leaving a dearl 
pocket at the lower half of the generating tubes. 

The special advantages claimed for this boiler are : 

1. The ability to revolve the lower superheater drum in its 
saddle, thus bringing the superheater tubes out into the open for 
examination and renewal. 

2. The lanes provided among the generating tubes in which the 
superheater tubes are located make it possible to give a more 
thorough examination to the outer half of the generating tubes of 
the boiler than was possible with the ordinary tube spacing, and also 
render it possible to renew tubes in the outer half of the nest with 
less sacrifice of good tubes to reach the faulty ones. 

3. The relative position of the superheater tubes in the lanes 
among the generating tubes provide the major baflling in the wake 
of the uptake, thus causing the gases in the lower half of the 
furnace to back completely through thfe lower half of the generating 
tubes instead of having a tendency to short circuit directly from 
the furnace up towards the uptake, leaving a dead pocket at the 
lower half of the generating tubes. 

4. By the arrangement of drums and lanes, the ability to increase 
and decrease superheating surface in comparison with generating 
surface becomes almost unlimited up to the 50-50 point. Also the 
large superheating surface gives a large area for the flow of steam 
through the superheater and reduces the drop through the super- 
heater to the lowest possible amount, a certain amount of drop being 
necessary in order to insure flow of steam through all the super- 
heater tubes. This is provided for by drypipe shown inside the 
superheater drums, which causes practically an even draft of steam 
to be taken from all parts of the lengths of these drums. While not 
shown in the drawing, at the upper ends of the three outer rows of 
superheater tubes ferrules are inserted decreasing the area of these 

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56 Marinb and Naval Boilers 

tubes at the upper ends and thus forcing more steam through the 
inner rows of tubes where the gases are of higher temperature. 

5. By inserting tubes in the lanes as shown, these lanes can be 
made of any depth desired, and the tubes extended into any tem- 
perature which may be desired. 

6. By having the superheaters so located as to roll out to the side, 
the length of firerooms may be brought down to a minimum instead 
of being limited by the space necessary to draw superheaters out 
from the front of the boiler into the fireroom. 

7. All steam connections can be made at one end of the drums 
and means can be provided for cutting out either or both super- 
heaters and for using either saturated, mixed or superheated steam, 
as may be desired. 

The steam connections are shown in the small plan. 

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Watbk-Tubb Boilers 67 

The Normand Boiler. 

The Normand oil-hurning boiler shown in Plate YI is installed 
on a number of destroyers. There are three cylindrical drums. 
The upper one shown in the plate is the steam drum A; the two 
lower ones are the water drums B. The steam drum is connected 
to each water drum by curved generating tubes C, and by a down- 
comer D, to each water drum at the back of the boiler. The front 
of the steam drum is tied to the front end of each water drum by 
a hollow, stay E; in addition to supporting the steam drum this 
stay acts as a small downcomer. 

Each boiler has one furnace fitted with oil burners. The boiler 
front carries an air casing F, through which air is admitted to the 
air cones 0, and through them into the furnace around each burner 
nozzle. Each burner has its individual air cone. 

The furnace gas bafiBing is arranged as follows : The inner rows 
of tubes^ C" (sectional plan)^ are bent back into the spaces between 
the second rows, C" (section at EF), making a baffle wall from the 
boiler front for a distance of about three-fourths of the length of 
the furnace. The tubes at the back of the boiler are spaced more 
openly from the end of the wall to the back of the furnace than the 
other boiler tubes. The two outside rows of tubes, C", are fitted in 
ttie same way for the whole length of the tube plates, and form a 
baffle wall between the tubes and the boiler casinsf. A vertical 

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58 [Marine and Xaval Boilers 

plate H (longitudinal section) extends from the steam drmn for 
a distance down through the tubes; the lower edge of this plate is 
shown (on section at EF) at H'. 

The circulation of the gases is shown on the sectional plan and 
on the longitudinal section by arrows, and is as follows : The gases 
flow to the back of the furnace, around the end of the tube wall, 
then towards the front, through the tubes, between the two 2-tube 
walls, and under the plate H. They thence escape to the uptake 
through the space I at the front of the boiler. 

The steam drum is made in two halves joined by treble riveted 
lap joints on each side. There is a manhole at the back, on top of 
the shell, and one in the front head. There is a handhole in the 
back head. The plate shows the method of lining the furnace; it 
also shows the air cones for the burners. 

The water oiroulation is from the steam drum A, through the 
rear downcomers D, and the stay rods E, to the water drums B; the 
steam and water rise through the circulating tubes C, and enter the 
steam drum in the water space. A short drypipe is fitted in steam 

The construction of the boiler itself is very similar to the coal- 
burning Normand boiler, shown in Fig. 36. 

This boiler is fitted on the torpedo boats of the Craven, Bagley 
and BlaJcely classes, and, in a slightly changed form, on the Owin 
class and on the Morris. It is also fitted on the scout cruiser Chester. 
It has small curved tubes which discharge below the water level. 
Fig. 36 shows a front elevation, half in section, of this boiler, as 
fitted on the Bagley class. The generating tubes are curved for the 
greatest part of their length, and enter the drums normally. The 
tubes forming the sides of the furnace do not meet in the middle 
at the top ; this small space is filled in with fire brick to protect the 
steam drum from the gases, and to close the small spaces left be- 
tween the upper ends of the two inner rows of tubes. The front 
and back of the furnace are built of brick. 

Bach side of the furnace, for about two-thirds of its length from 
the front, is formed of a wall of tubes ; in the remaining one-third, 
the tubes are open and permit the gases to pass between them. The 
sides of the grate are brick walls, which not only protect the lower 
drums and lower ends of the tubes, but also close the small spaces 
at the bottom of the tube wall. The two outer rows of tubes in 
each nest are bent to form a wall, which is complete, except at the 
upper part for about one-third the length from the front. The 

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rest of the generating tubes are staggered. By this arrangement, 
the products of combustion are forced to enter between the open- 
spaced tubes at the back. They then return between the tubes and 
rise, through the open spaces left in the outer wall, into the uptake 
at the front end of the boiler. 

Fio. 36. — ^Normand Boiler (Express Type, Coal-Burning). 

In the twelve boilers for the Chester, which are like Pi^. 36, the 
steam and water drums are 40" and 18" in diameter, respectively, 
and have welded joints on the shell. The grates are 7' 2i" long, 
and the tubes IJ" in outside diameter, and .134 thick. The down- 
comers in this case are at the front of the boiler and the uptakes 
are at the back. This causes the tube walls next to the furnace to 

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60 Marinb and Naval Boilers 

be open at the front of the boiler, which just reverses the circulation 
of the gases of combustion, as given above, for the Bagley class. 

The Thomyoroft Boiler. 

A Thomycroft boiler, fitted for burning liquid fuel alone, is 
shown on Plate VII. This plate shows the method of securing 
the fire brick lining the furnace, the front casing fitted for admit- 
ting air to the burners, the burner openings and the method of 
baflBing for gas-circulation. 

This boiler is fitted in the A mmen. Burrows, McCall, Monaghan, 
Roe and Terry, 

As may be seen from tho plate, it has one steam drum and two 
water drums; the tubes, of seamless-drawn steel, all enter the 
steam drum in the water space. There is one large downcomer 
tube from the front end of the steam drum to each water drum; 
the steam drum projects through the front casing and the down- 
comers are outside of the casing. There are no baffles or passes to 
cause the gases of combustion to circulate in any particular way 
through the tubes ; the fiow of the gases is direct. A deflecting plate 
A is placed in the uptake space and prevents the gases from passing 
from the top of the furnace direct to the uptake. The gases pass 
through a reduced opening between this plate and the casing. This 
keeps the hot gases of combustion in contact with the heating 
surfaces of the boiler for a longer period of time and prevents high 
smoke-pipe gas temperatures. The boiler casing is constructed of 
galvanized steel plates and angles, lagged on the inside with 
asbestos and magnesia. In the wake of the tubes this casing is 
made in sections to allow for examination and repairs. At the 
back of the boiler there is a 2" air space between the non-conducting 
lining and the plates. The front casing, between the downcomer 
tubes and the bottom of the ash pans, has an air space 15" in depth, 
and it is fitted with light air-regulating doors admitting air from 
the fire-room into the casing. The amount of the opening of the 
doors can be regulated ; in case of a large steam leak in the furnace, 
they close automatically. The furnace is lined at the front and 
back, and at the sides, up to the water drums, with fire-brick tile 
2^" thick and 9" square. The bottom of the furnace is lined with 
fire brick 1^" thick by 9^^ square, laid in two thicknesses so as to 
break joints. Sight holes are placed so as to permit observation of 
the products of combustion. The.downcomers and all tubes are 
expanded into the drums. 

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Water-Tube Boilers 61 

There are at present four types of Thomycrof t boilers in the navy, 
of which the one in Plate VII is the latest. It is a radical change in 
design from the first three, which vary among themselves only in 
arrangement of drums and tubes. The Thomycroft principle up to 
this last type has been to have all generating tubes enter the steam 
space of the steam drmn. Many of the water-tube boilers with accel- 
erated circulation were originally designed to have the upper end of 
the tubes enter the steam space, but practically all of them have 
changed to having the tubes enter the water space of the steam 
drum; in other words, the upper ends of the tubes are '* drowned/' 

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FiG. 39.— Thornycroft Boiler (Ohio Type). 

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Water-Tubb Boileus 63 

Ohio Type. — The original Thornycroft principle is illustrated in 
the Ohio type of boiler, shown in Fig. 39. This type is a combina- 
tion of the several types of coal-burning Thornycroft boilers. It is 
fitted on the Ohio, Missouri and Ozark. 

The wing drums are of the same size as the central water drum, 
and are fitted with a large number of generating tubes. The down- 
comers B and C, C are outside the casing. There are two lofty 
furnaces, the sides and tops of which are formed by the wall in 
each nest of tubes. The gases of combustion from the furnace enter 
the openings at the bottom on each side, rise between the inner and 
outer walls of each nest, and pass through openings at the top into 
the uptake V directly above the tubes. The heart-shaped space B 
is, therefore, not used as a connection for the gases. The openings 
in the front of the casing, when the closed fire-room system of 
draft is used, are the same as before. They consist of non-return 
air doors K, K by which the supj^ly of air above the grates can be 
regulated; sight doors 8, 8 for the examination and sweeping of 
the tubes; and soot doors 2>, D for the cleaning of the heart-shaped 
space B. The generating tubes vary from IJ" to If" in diameter, 
and, as in the previous types, discharge the water and steam into 
the drum Y above the water-line. 

Although the Thornycroft boiler is extensively installed in the 
TJ. S. Navy, its complicated structure and the diiBculty of cleaning 
and repairing it have, in recent years, prevented a continuance of 
its installation. 

The Tarrow Boiler. 

The Tarrow boiler for burning oil fuel, shown in Plate VIII, is 
a straight-tube boiler of the accelerated-circulation class. Several 
destroyers are fitted with boilers of this type. The coal-burning 
boilers of the Yarrow type are practically the same as the oil burners, 
the difference being in the details of the furnace front and furnace. 

The Yarrow boiler is used extensively in the British Navy in 
both the large-tube and the small-tube types. 

The boiler consists of a steam drum and two oval water drums; 
each water drum is connected to the steam drum on ita own side 
by straight seamless-drawn steel tubes, expanded into each drum. 
The steam drum is made up of a top drum sheet and a tube sheet, 
butt-jointed with double butt straps. The joints are on a line 
parallel with the axis of the drum. The tube sheet is made much 
thicker in wake of the tubes. 

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64 Mabinb and Naval Boilers 

The water drums are made up in the same manner^ except that the 
drum sheet laps over the tube sheet and the joint is double-riveted. 

Water Circulation. — The feed water enters the steam drum, and 
flows down to the water drums through the tubes furthest away 
from the fire; the steam and water flow up to the steam drum 
through the hottest tubes. Some types of the Yarrow boiler have 
downcomers outside the boiler casing. Without downcomers the 
water circulation varies under the diflEerent conditions of steaming, 
and different degrees of steadiness of the ship. Tubes which, under 
certain conditions, act as downcomers, change to generating tubes 
with the changed conditions. Although the circulation path of 
the water is slightly in doubt, it is certain that the circulation is 
satisfactory, as there are many boilers of this type in successful 
operation. In some of the early Yarrow boilers an inclined flame 
plate partially blanked off some of the outer tubes from direct 
impinge of the flame, in order to keep the outer tubes cooler and 
have them serve as downcomers. 

The latest system is to discharge the feed water into both lower 
drums through an internal feed pipe extending nearly the entire 
length of the drum. The internal feed pipe discharges into a 
pocket formed by a steel plate curved around the internal feed pipe, 
closed at both ends and shaped to direct the water upward through 
the two outer rows of tubes. Where the water discharges into the 
upper drum, a short baflBe is so fitted as to direct the water outward 
toward the surface of the steaming level. The circulation is in- 
creased, and the system has resulted in a more satisfactory per- 
formance of the boiler. 

Furnace-Gas Circulation.— The gas-baflling system of the Yarrow 
boiler is very simple. An inclined flame plate A is secured at the 
upper end of the outboard row of tubes. The gases in the upper 
part of the furnace are deflected down by this plate and prevented 
from passing directly to the uptake. The opening to the uptake 
at C is reduced, in order to retard the flow of the gases and prevent 
high smoke-pipe temperature. In addition a flame plate B crosses 
the tubes at right angles about midway of their length. This plate 
retards the flow of gases somewhat and also causes a change in theii 
direction on the way to the uptake. 

Boiler Casing. — ^The casing is made up of galvanized steel plates, 
angles, brick-work, asbestos board and magnesia. The uptake casing 
has three sheets. Between the inner and middle sheets there is an 

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Watbr-Tubb Boilers 66 

air space; between the middle and outer sheets there is non-conduct- 
ing material. The furnace fronts and backs consist of galvanized 
steel plates, between which is placed asbestos board and magnesia ; 
to the inner of these plates is secured a layer of 2" brick-work 
secured as shown. The bottoms and sides of the furnace up to 
the water drums are covered with two thicknesses of 2" brick, 
arranged to break joint. The front casing carries openings for the 
burners and their air cones in an enclosed compartment fitted with 
self-closing doors for regulating the air supply. There are doors 
in the casings in wake of the tubes for cleaning the tubes. There 
are observation windows just below the uptakes, and sight holes 
for observing the conditions of combustion. 

Manholes, etc. — ^There are manholes in each steam and water 
drum; through these, leaky tubes can be plugged or expanded and 
cleaned. One of the advantages of the Yarrow boiler is its sim- 
plicity of construction. One of its disadvantages, and in fact one 
of the great disadvantages of most boilers with accelerated circu- 
lation, is that it is a very diflBcult matter to replace tubes without 
completely retubing one side. Tubes in the inner and outer rows, 
however, can be replaced easily. 

The White-Forster Boiler. 

The White-Porster oil-burning boiler, shown in Plate IX, con- 
sists of a large steam drum and two water drums, connected by 
relatively short tubes. In manufacture the tubes are curved in one 
plane only, and with the same radius of curvature ; when placed in 
the boiler, however, a curvature both towards the furnace and 
toward one end of the boiler is obtained by slightly revolving the 
tubes before expanding them into place. This is plainly shown in 
Figs. 1 and 2, Plate IX. 

The construction of the steam and water drums is similar to that 
described for the Yarrow boiler, except that the water drums are 
of circular cross-section and have the two sheets of the drum secured 
by means of double butt-strap joints, as shown. There is a manhole 
near the top of the front steam-drum head and one in the front 
head of each water drum. Large downcomer tubes at the back of the 
boiler connect the steam drum to each water drum. 

The curvature and length of the generating tubes are such that 
a tube can be removed or replaced from the steam drum through 
the manhole. 

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66 Marine and Naval Boilebs 

They can be cleaned from the steam drum. The ends of the 
tubes can be expanded from the steam and water drums. Any 
tube can be withdrawn without disturbing the remaining tubes. 

The water circulation is from the steam drum down the down- 
comer tubes to the water drums^ and up the generating tubes to the 
water space of the steam drums as water and steam. No special 
water bafSes are installed. The dry pipe, internal ^ed pipe and 
scum pan are the only internal fittings. This boiler, with its large 
steam drum, is noticeably free from priming, on account of the 
larger disengaging surface, which permits the steam bubbles to pass 
freely through the surface of the water without violent ebullition. 

The circulation of the furnace gases is shown by the arrows in 
the plate. BaiQe plates are fitted as shown at A, and B. The open- 
ing at the bottom of the uptake is reduced in area to retard the flow 
of the gases and prevent high smoke-pipe temperatures. 

Some of the good points of this boiler are: (1) Its simplicity of 
design and c;/nstruction. (2) Any tube can be replaced with ease. 
(3) The curvature of the tubes allows for expansion. (4) It is 
easy to clean, inspect and repair. 

The coal-burning White-Forster boiler differs from the oil-burn- 
ing boiler only in the details of the furnace front and furnace. 

The White-Forster boiler is installed in the Warrington, Mayrant, 
Patterson and Beale. 

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Watkb-Tubb Boilebs 67 

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68 Mabins and Naval Boilers 

The Ward Boiler. 

Nearly all of our launches are fitted with this type, which was the 
standard boiler for steamboats. These boilers are either cylindrical 
or square in shape, the arrangement of tubes and other parts being 
shown in Fig. 43, which is a cut of a cylindrical boiler. 

Bound Type. — A circular manifold A, of cast steel, with a hollow 
projection for the furnace door opening, forms the base of the boiler 
and supports the grate. This manifold rests on a cylindrical ash-pit 
structure which is secured to the keelson. On the upper surface of 
the manifold there is a row of holes, into which vertical tubes of 1^" 
inside diameter are secured by tapered screw couplings. These tubes 
are straight except at the top, where, by an easy curve, they are bent 
through 90**, and enter the vertical drum D, to which they are 
secured by tapered screw couplings. The upper part of the drum is 
of plate steel and cylindrical, and the lower part of cast steel, cylin- 
drical where the bent tubes enter it and conical below that. As the 
diameter of the manifold is about 2^ times that of the drum, the 
tubes of each row from the manifold cannot enter the drum in the 
same horizontal plane. Half the tubes enter the drimi in one hori- 
zontal plane and the other half enter in a slightly higher plane. 

Into the conical bottom of the drum, a number of straight Field 
tubes T, of wrought iron or steel, usually 1^' internal diameter, 
are screwed. These tubes project into the cylindrical space inside 
of the vertical tubes and above the fire. The outer or lower end of 
each hanging tube is closed by a screw cap, and its inner end by a 
tight-fitting plug, in which are two small holes. Into each hole is 
fitted a small brass tube, open at both ends, one tube extending 
inside of the hanging tube to within an inch of the bottom, and 
the other and shorter one projecting about 4" into the drum. This 
is shown in the section of the outer hanging tube. 

Around the inside of the drum, an inclined diaphragm P is fitted 
below the openings of the lower row of vertical tubes. This dia- 
phragm separates the main generating tubes from the downcomers. 
By means of the internal feed pipe not shown, the feed water is deliv- 
ered to the lower row of tubes, going thence to the manifold and 
returning to the drum by the tubes that enter highest. From the 
drum the water goes down the long brass tube inside T, where steam 
is formed which returns to drum through the short brass tube. 

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Fig. 43. — Ward Launch Boiler (Round). 

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70 Marine and Naval Boilbrs 

Square Type. — Pig. 44 shows the outside of the Ward steam- 
launch boiler, square type. The principles involved are the same as 

Fio. 44.— Ward Boiler (Square). 

in the round boiler, the only difference being that the lower manifold 
(S square. 

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Watbr-Tubb Boilbrs 71 

Type W Launch Boiler. 

The Type W launch boiler, which is being built for a new class 
of 50-foot steam launches^ is shown in Plate XI. This boiler was 
designed in the Bureau of Steam Engineerings and is built at the 
New York Navy Yard. 

It has a steam drum and two water drums^ connected by slightly 
bent generating tubes. The outer row of tubes in each nest acts as 
a downcomer, the feed water being directed into them from the 
internal feed pipe^ as shown at J. in side elevation. 

The water circulation is down the outer row of tubes to the water 
drums^ and up the inner rows of tubes^ as steam and water^ to the 
steam drum. To aid the water circulation, by keeping the outer 
tubes cooler than the inner ones, bafBe plates are installed between 
the middle rows of tubes in each nest; they extend from the steam 
drum about half way to the water drum, and from the front to the 
back of the boiler. These are shown in the transverse view. 

Steam is drawn from the steam drum for use through the dry 
pipe near the top of the drum. There is a manhole in the front of 
the steam drum and a handhole at each end of each water drum. 
The boiler has a short grate with large heating surface. It has the 
fittings found on all large boilers. 

The circulation of the gases of combustion is practically direct 
from furnace to smoke pipe. 

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Marine and Naval Boilers 

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The fittings * absolutely necessary on a marine^ or^ in fact on an; 
boiler, are : 

(a) On steam side of boiler : 

1. Steam stop valves for regujatiag the flow of steam to the steam 
pipes or for closing the steam off the pipe. 

2. Dry pipe in steam drum or shell for preventing foam or water 
from being carried into the steam pipes. 

3. One twin or triple safety valve, set to lift at the desired 

4. Steam gages for recording pressures above the atmosphere. 

5. One set of three-gage cocks, arranged to show the approximate 
level of the water in the steam drum or shell. 

6. At least two glass water gages to show the level of the water in 
steam drum or shell. 

7. One air cock, placed at highest part of steam space, for letting 
the air out of the boiler as it is pumped up, or as steam is formed in 
the boiler. 

(b) On water side of boiler : 

1. Feed stop and check valves, for admitting feed water into the 
boiler, with internal pipes for its distribution, so that one part of the 
boiler will not be kept cooler than another. 

2. Surface blow valve, internal pipe and scum pan, for removing 
grease or foam from the surface of the water in the drum or shell. 

3. One or more bottom blow valves, for removing dirty water, sedi- 
ment or loose scale from the bottom of the shell, water drums or 
uprights, for blowing down the boiler to reduce the saturation of the 
water when it gets too high, and for drawing off the boiler water by a 
pump. In fire-tube boilers and in some water-tube boilers with long 
water drums, internal pipes are connected to the bottom blow valves. 

4. One or more drain cocks placed for drawing all of the water 
out of the boiler at the lowest part of water space. 

6. One connection for drawing water from the boiler for test. 

The boiler fittings will now be taken up and described. 

Self-Closing Stop Valve, Closing toward the Boiler. — In the 
earlier designs, all boilers were fitted with one main and one 
auxiliary stop valve, connected, through openings in the shell of the 
boiler or stetun drum, with the dry pipe. In later designs, these two 

* Specifications for boiler fittings will be found in Appendix. 

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74 Mabinb and Naval Boilers 

valves are in the same casing, thus requiring only one opening to 
be cut in the shell. In the recent large ships with water-tube boilers, 
where the main steam pipe takes steam from the boilers only in- 
directly, by way of the auxiliary pipes, there is only one stop valve 
on the drum, which is called the main stop valve. An automatic 
stop valve is fitted in the auxiliary pipe from the boiler to the main 
steam line near where the former joins the latter. 

In the older ships, with fire-tube boilers, these steam stop valves 
were self-closing toward the boiler. 

The ordinary form of self-closing valve, with part of the gear for 
working it from the deck, is shown in Fig. 45. G is the valve 
chamber, with inlet at I and outlet at 0, in this case at right angles 
to I. 

The lower view is a vertical section through the center, and the 
top one, a plan of the outside with parts omitted for clearness. 

The valve V is secured to the valve stem S, as shown in the 
sketch. A short distance above the top of the stuffing-box, S is 
reduced in diameter and ends at the cross-bar handle H, which is 
pinned to it. The hand wheel W does not, as in the ordinary stop 
valve, raise and lower the valve, but only regulates the amount of 
opening which may be given to the valve. 

Surrounding the reduced part of iS^ is a threaded sleeve F, which 
may slide on 8. The thread on F works in that of a bushing N, 
which may turn in the steel yoke E, but is prevented from rising 
by the flange or collar which bears against the under side of E. 
The bushing extends to the under side of wheel W. Between W 
and the top of E is the bevel wheel B, which is screwed on and 
keyed to tiie bushing, and to which is bolted the hand wheel. 
Qeared to £ is the bevel wheel C, which can be turned by the 
small shaft D leading to the deck. D turns in and is supported 
by a bracket bolted to L. Yoke E is held in place by two studs 
screwed into the bonnet L of the valve. On these studs slides t 
forked guide, not shown, which is secured to the lower end of F. 
This guide keeps F from turning, but allows it to have sliding 
motion on S. 

When W is turned, either by hand or by means of the bevel 
gear, bushing N turns, and sleeve F will, therefore, move along 8, 
rising into the opening A at the top of N. When F has been 
moved the required distance, stem 8 and the valve are pulled 
out, or the valve is opened, until the enlarged part of S is stopped 
by F. When the valve is being opened, handle H should always 

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BoiLKB Fittings 7!) 

FiQ. 46.-- Self-closing Stop- Valve, Closing toward Boiler. 

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76 Marinb and Naval Boilers 

be pulled out as W is turned, in order to prevent the violent opening 
of the valve when the excess pressure under it is great enough to 
overcome the friction in the stuffing-box. As a safety precaution it 
is always well to have the pressure in the boiler a few pounds higher 
than in the line to be connected; then the valve is sure to follow up 
the motion of the sleeve F. 

These valves are fitted to boilers and pipes in a horizontal posi- 
tion, when possible, so that the weight of V and S will not enter 
as a factor in their movement when differences of pressure occur 
on the two sides of 7. If fitted in a vertical position, the move- 
ment of V may be a violent one, and large valves have been broken 
from this cause. They are, however, easier to keep tight when 
fitted vertically. 

Ordinary Stop Valves. — In the old style of stop valve the seat of 
the valve was beveled. Lately the practice has been to make the 
valve seats flat. There are numerous makes and various types of 
valves in use. Fig. 46 shows an ordinary screw-down stop valve 
made by Jenkins Brothers, and illustrates the principles involved. 
This valve consists of the following parts : 






Valve stem. 


Guide stem. 




Gland stud. 


Disc nut. 




Yoke stud. 


Seat ring. 


Wheel nut. 


Lock nut. 


Disc holder. 


Jam nut. 




Cotter pin. 


Yoke nut. 


Disc plate. 

Nos. 1 and 8, in the table above, are made of cast steel, cast iron 
or composition, depending on the service required; composition can 
be used in case of water valves or valves in lines carrying saturated 
steam ; cast steel can be used with saturated steam ; cast-iron valves 
are not used aboard ship, but are used extensively on shore for 
various purposes. 

The other items in the table, except the yoke studs, are made of 
composition or Monel metal. The yoke studs are of composition or 

The operation of this valve can be easily understood from the 
sketch. It will be noticed that both the seat and disc can be renewed. 
The introduction of fiat seats is due to the fact that, with modem 
high pressures, the bevel form of valve, having a small seating area, 
was quickly eroded by the fiow of steam when opening or closing 

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BoiLEB Fittings 111! 

the valve. The flat valve has a larger seat area^ and the erosion 
takes place only on the inner edge of the seat and outer edge of the 
valve. In addition, the flat valve accommodates itself more readily 
to the varying expansions of the valve and seat and remains tighter 
under temperature changes than the conical valve. 

Fig. 46. — Ordinary Stop Valve. 

These valves are always installed in such manner that they seat 
against the pressure. In the naval service they are made to close 
right-handed, i. e,, in the direction of the hands of the clock. Where 
used as stop valves on boilers or as engine stop valves, gearing is 
fitted to open and close the valves from the deck overhead, and from 
floor plates of engine- and fire-rooms. Large valves of this class 
are fitted with bypasses to equalize the pressure on both sides of the 

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78 Mabinb and Naval Boilbhs 

valve before opening. Such a bypass is shown at M, in line sketch, 
Fig. 47. The line sketch of Fig. 47 is added to show the usual 
measurements required in ordering valves. 

Fig. 48 shows a screw-down globe valve, fitted for screwed pipe 
connections, with flat valve face, renewable seat, the valve disc 
being fitted to project through the opening below valve seat. This 
disc prevents steam from blowing through and cutting the disc and 
seat as the valve is leaving the seat when being opened. 


Fig. 47. — Bypass Valve. 

A — ^Face to face, screwed. J — Diameter of hand wheel. 

B — Face to face, flanged, standard K — Center of main valve to center 

flanges. of bypass. 

E — Diameter of standard flanges. L — Center of bypass to extreme 
F— Thickness of standard flanges. outside. 

O — ^Main valve, center to top of M — Height of bypass, open. 

hand wheel, open. "N — Size of bypass. 

The metal of the body and disc of the valve is composition, and 
the seat is hard, close-grained nickel. 

Dry Pipes. — In each boiler or steam drum, a tliin steel pipe is 
fitted as near the top as possible. This pipe extends nearly the 
length of the boiler or drum, and is perforated on its upper side with 
slits or holes, of such number and size that the sum of their areas 
is equal to that of the steam pipe leading from the boiler. TIsually 

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one end of this pipe is secured to the stop-valve nozzle and the 
other end is closed. Steam from the boiler can, therefore, get into 
the stop-valve chamber only by rising nearly to the highest point 
in the steam space^ and thence through the slits in the top of the 
dry pipe. As this pipe extends nearly the whole length of the 
boiler^ the steam is collected from all parts of the steam space 
instead of rushing up from one place into the large stop-valve 

Fig. 48. — Globe Valve, Small Type. 

nozzle. The evaporation is, therefore, more uniform, and any ten- 
dency to priming is much reduced. For the same reason, safety- 
valve chambers are now connected to the dry pipe, either directly 
or through the stop-valve chamber, instead of opening directly into 
the steam space. 

One or more small drain holes are made in the under side of the 
dry pipe to prevent accumulation of water. 

The dry pipes and drains to the steam drums must be exam- 
ined frequently to ascertain if the holes in them are clear. 

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T-Casting for Steam Distribntion. — Fig. 49 shows a T-casting. 
which reduces the number of holes to be cut in the boiler shell for 
the various stop and safety valves to one, all valves taking steam 
from the dry pipe. 

G is the boiler shell, to which is riveted the nozzle F, which 
forms a seating for the casting E. F also strengthens the shell to 
compensate for cutting the hole. To the internal spigot of F is 
fitted a vertical branch H of the dry pipe, the latter being hori- 
zontal and closed at both ends. A is the flange to which the 

Fro. 49. — Steam Connection to Dry Pipe. 

dynamo stop valve is bolted, and D that for the auxiliary stop 
valve, both self-closing, with their spindles horizontal. B is the 
seating for the main stop valve, and C that for the safety valves. 
The spindle for the main stop valve is, in this case, vertical. 

These T-castings are installed on many of the ships now in the 
naval service. The present practice is to have a boiler opening for 
each fitting, with the number of fittings reduced to the lowest 
number practicable. The practice varies somewhat at the various 
shipbuilding plants. 

Feed Stop and Check Valves. — ^The latest types of these valves 
are fitted with an internal pipe to discharge the feed water up toward 
the steam space. 

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BoiUER Fittings 81 

Each boiler has two of these combined valves, entirely separate 
from each other, one connecting the boiler to the main feed pipe, 
and therefore called the main check valve, and the other to the 
auxiliary feed pipe, and called the auxiliary check valve. Except 
for steam launches, two valves are always provided, for safety, in 
case one of the feed systems should fail to work. 

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82 Marine and Naval Boilebs 

Fig. 50 8how8 a recent form of check valve. Between the check 
valve K and the dnun there is the stop valve 0, by means of 
which conmiunication with the boiler can be shut off, thus allow- 
ing the check valve to be overhauled, if necessary, when steam is on 
the boiler. 

The valves are in the composition chamber H, with inlet for 
the feed water at Q and outlet through the nozzle at L. The 

Fio. 60. 

check valve K can move up and down freely, the amount of move- 
ment or opening being regulated by the collar D on the valve stem C 
and handle A. B is the yoke. iV is a standard bronze flange. F is 
the internal feed pipe by which the water is led to the point or 
points of delivery. 

In the flgure, the stem is shown screwed down to close the valve 
entirely. The valve is guided below the spindle and above by the 

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socket, in which the short cylindrical projection of C can move 
freely. The phosphor bronze spring P helps to close the valve when 

When steam is on the boiler, the stop valve is kept open and 
the boiler pressure will then be on the back of valve K, and keep 
it shut. When the boiler is to be fed, A is turned slightly, thus 
raising the collar on (7 a certain distance and leaving a space be- 
tween it and the top of the valve K. The valve can now lift 
through that distance whenever the pressure below it in the feed 
pipe is greater than that on the back. This will happen during the 
early part of the stroke of the feed pump; towards the end of the 
stroke, as the pressure decreases, the valve will be forced down by 
the boiler pressure and spring. This alternate opening and closing 
of the valve with the strokes of the pump produces an audible click. 
If this is not heard, the check valve is not working properly and 
should be examined. Should the feed pipe near the valve chamber 
be very much hotter than the rest of the pipe, it is evident that the 
check valve leaks. Small holes R are drilled at the bottom of the 
guide or socket on K for the escape of water as the valve lifts. 

In fire-tube boilers, the internal feed pipes run along the length 
of the boiler above the tubes, the main pipe on one side and the 
auxiliary pipe on the other. 

In water-tube boilers, as in Fig. 50, the feed check and stop valves 
are on the steam drum, and, owing to the height of these drums 
above the fire-room fioor, gear for working the valves from the floor 
plates is provided. This hand gear is shown in Fig. 50b. 

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Mabinb and Naval Boilers 

The bottom of the outlet nozzle L is always well above the seat 
of £", to ensure a water seal on top of the valve. The stems of 


,S^r WAem/3 


I I 


3 — CZJ 



Fio. 50b. 

both check and stop valves^ like all other valves on boilers, have 
•crew threads outside of the valve chamber. 

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Boiler Fittings 85 

In order that the amount of feed water supplied can be regu- 
lated for each boiler separately, without varying the speed of the 
feed pump, the latter is fitted with a relief valve. 

Feed Check Valve for Steamers. — Fig. 51 shows a section of 
a simple form of check valve which is sometimes fitted to the feed 
pipe of steamers and other small boilers. It is also frequently 
used in pipes to prevent the return of the water. 

The valve swings on a pin, which can be removed by unscrewing 
a plug in the side of the chamber. As will be noticed, the valve 
will open only to let in water from the left, into which end is 
screwed the discharge pipe of the feed pump. The right-hand end 
is screwed on a nipple in the boiler, and the back of the valve is 
held down by the boiler pressure. 

Fm. 61. — Fteed Check Valve. 

When the valve is to be examined, the top cap is unscrewed. 
Shoxild the valve leak, it can be groimd and fitted to its seat by 
inserting a grinding tool through the inclined hole on the upper 
side, after removing the plug there. 

Internal Feed Pipes. — ^The internal feed pipe is an extension into 
the boiler of the external feed pipe. It is necessary in order to carry 
the inflowing water clear of the metal in the vicinity of the opening 
and distribute it evenly in the drum or shell, so that air and other 
injurious ingredients in it will not corrode the metal around the 

The latest method of installing the internal feed pipe is to lead 
it along nearly the entire length of the drum, with its top about 
%" or T below the normal water level when steaming, with the 
openings upward so that the water will be discharged into the water 
space about the middle of the drum. This arrangement forces 
the air entering with the feed water toward the steam space and 
lessens neatly the quantity of air circulating through the boiler. 

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Marine and Natal Boilbrs 

J^cr/^?A^ /t'SC/?'S'/: 

Fio. 54.- 

Surface Blow Valves. — Ordinary screw-down globe valves made 

extra heavy are used for surface blow valves. These valves close 

against the boiler pressure. 

Fig. 53 shows the method of fitting 

the internal blow pipe C7 to the valve 

casting A. The latter has a nipple or 

spigot which projects through the shell 

of the boiler or drum B, and makes a 

tight fit with the pipe which has been 

expanded into the shell. The valve is 

secured by bolts, not shown, passing 

through the shell and the valve flange. 

The latest method of installing the 
Pig. 63.— Method of Fit- - , , . • . i j -j. i xi. 
ting Internal Blow Pipe to «^^^»<=« ^^°^ P^f '^ *« ^^^ ^* "^'^'^g **>« 
Yi^lye. entire length of the drum m a position 

where the water in the drum has the 
least motion. It is placed about 2" below the normal water level 
of the drum, and has slots on the upper side along its entire length. 
Bottom Blow Valves. — Specifications for the battleships New 
York and Texas call for IJ" bottom blow valves on each boiler, 
located where approved; to be of the seatless hollow piston type 
without any projection upon which sediment or scale can accumu- 
late ; the pressure to be against the side of the piston, when closed ; 

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BoiLEB Fittings 87 

ttom Blow ValTe. 

tlie piston to have an opening in the side, which, when the valve is 
open, will present a full unrestricted area for blow-off. The term 
*' seatless '^ is a trade name for a type of valve which does not depend 
for its watertightness on a valve fitting a seat. Packing around a 
piston accomplishes this. 

Such a valve is shown in Fig. 64. The flange A bolts to the 
upright or water drum. Pressure is on the piston 2, around the 
whole of its circumference, through the opening in valve body at BE. 
The piston is hollow from CD to its outer end, with openings at CD. 
It is moved by the hand wheel 7, turning the valve stem 5, which 
works loosely between the wheel and collar through the yoke 6. 
The valve stem is threaded at 6, and moves the piston 2 by screwing 
through it, 2 being prevented from turning. The two turns of pack- 
ing at 4, on each side of the opening BE, on the valve body, make the 
joint between the piston and valve body tight. The gland 3 sets 
up on the packing at 4 and (through the distance piece) at 4. The 
studs to hold the gland in position are not shown. 

All of the discharges from the surface and bottom blow valves 
join in one common discharge to the sea through an independent 
sea valve. The valve is opened by working the hand wheel until the 
opening at CD comes in line with BE, when the water will be blown 
out at M. 

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88 Mabinb and Natal Boilers 

Formerly^ when salt water was used for make-up feed, the bottom 
blow valve was also used to blow out the denser brine from time to 
time, and this, by permitting the introduction of new and less con- 
centrated sea water through the feed valve, helped to keep the con- 
centration of the water in the boiler below the required limit. It was 
also used to blow down or blow all of the water out of the boiler, 
when through steaming and after the fires were hauled. The IJ. S. 
Naval Instructions for the Care, Preservation and Operation of 
Boilers prescribe the limits of concentration in the various types 
of boilers below which the bottom blow should not be used. 

It often becomes necessary to get rid of mud or other sediment 
from dirty fresh water, and for this purpose the bottom blow may 
be used while the boiler is under steam. This is especially necessary 
in water-tube boilers. The Babcock and Wilcox Company recom- 
mend that the bottom blow be used at least twice a day when 
steaming regularly, by opening the valves wide and immediately 
closing them. A more frequent and freer use is recommended when 
the boilers are under banked fires or steaming slowly, as, on account 
of the less active circulation under these conditions, there is greater 
opportunity for deposits to settle on the heating surfaces. 

The bottom blow valve also serves another purpose. Through 
a pipe connection, leading from the blow pipe in each compari- 
ment to the auxiliary feed pump, the water in any boiler may be 
pumped out, by opening the bottom blow valve, after steam is off the 
boiler, and discharged overboard or into the reserve tanks or boilers. 

Safety Valyes. — These are fitted to prevent the pressure in the 
boiler from rising above the safe working limit and to provide a 
ready and automatic means of escape for the surplus steam. This 
is accomplished by opposing the resistance of a spring, acting on 
one side of a valve, to the steam pressure in the boiler acting on 
the other side, the chamber into which this valve opens being con- 
nected to the atmosphere by the escape pipe. 

Figs. 1 and 2, Plate XII, show examples of duplex pop safety 
valves of the navy pattern, the first showing an outside and a sec- 
tional view of the valve made by the Star Brass Manufacturing 
Company, and the second, a sectional view of the improved valve 
made by the American Steam Gage and Valve Company. The 
general appearance of the outside of the American valve and its 
Ufting levers and shaft is similar to that of the Star valve, so that 
only one outside view is shown. 

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Boiler Fittings 89 

These valves^ as well as those made by other manufacturers, 
conform to the requirements of the Bureau of Steam Engineer- 
ing. The type shown here is called the " Duplex/' on account of 
two Yalves being enclosed in one casing. They are also made in 
the single, triple and quadruple types, but the valves are the same 
for all types of the same make. The usual requirement is that 
two or more safety valves shall be fitted, instead of having the 
necessary area put into one valve. The valves are, whenever pos- 
sible^ placed vertically. When placed horizontally^ owing to the 
play between the wings of the valve and the seat, they are very 
hard to keep tight. « 

Eef erring to Plate XII, A is the valve casing, its lower part C 
having usually a separate and direct connection to the boiler, and 
its upper part being connected to the escape pipe by the flange B. 
When C is connected to the main stop-valve casing, it must be 
between the boiler and the stop valve. In both cases, steam is taken 
from the dry pipe. 

Bolted to the top of A are the two cases W, W, for the springs, 
each being so fitted that the valve V can be taken out without 
interfering with the adjustment of the spring P. 

To move the valve by hand, the lever L, working against the 
cap E, which is secured to the valve stem T, is provided. By 
means of the link and arm shown, L is connected to a rock shaft Q. 
This shaft is turned by suitable lifting gear, either from the fire- 
room or from the deck above, the rock shaft arms being so ar- 
ranged that the valves in each casing are lifted in succession 
and not together. By means of the handle secured to the valve 
stem T, the valve T can be turned on its seat S without inter- 
fering with any other part. Any scale or dirt which may have 
lodged between the valve and seat can thus be removed. To pre- 
vent an accumulation of water from the condensation of escaping 
steam, a drain pipe leading into the bilge is attached to the opening 
M below the level of the adjusting ring X. 

The Spring. — The spring F is of the highest quality of steel, 
nickel-plated, and square in section. It is enclosed in the case 
W, io prevent contact between it and the steam and so reduce the 
chances of corrosion. Each spring is made long enough to allow 
the valve to lift one-eighth of its diameter when the valve has been 
set at the designed working pressure. To overcome the effect of 
any tilting of the spring when the valve opens, and consequent 

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90 Mabikb and Naval Boilebs 

binding of the wings of the valve against the sides of the seat 8, 
the ends of the spring must be free to oscillate. This is accom- 
plished in the American valve, Plate XII, Fig. 2, by inserting the 
independent flanges F, F, which have spherical bearings where they 
rest against the valve stem T. 

In the Star valve, Plate XII, Fig. 1, the lower flange 0, called 
the compression plate, is pivoted on the valve, and has two projec- 
tions which fit into slots cut out of the screw ring H. These slots 
permit the ends of the projections to move up and down when the 
spring tilts, without communicating this motion to the valve, the 
wings of which, therefore, remain truly in line with the sides of 8. 
When the valve is to be examined, the slots in H allow the case 
W, valve stem T, spring P, and compression plate 0, tohe lifted 
out together, the valve V remaining on its seat. In the American 
valve, Plate XII, Fig. 2, the valve V is lifted with the spring, to be 
disconnected after removal by taking out the small set-screws and 
unscrewing the small nut shown on top of the valve. 

The casings A and W and valves V are made of standard com- 
position for strength and to prevent corrosion. The valve stem T 
is made of rolled bronze. The springs are adjustable for pressures 
up to the test pressure of the boiler. 

The Valve. — ^The valve seat jS is a solid nickel casting screwed 
into the casing A, and extends down to the bottom of the wings 
on the valve V. It is turned to a cylinder on the inside and 
serves as a guide for the wings of the valve these being slightly 
smaller in diameter to prevent binding. On the top of iS a narrow 
conical seat is turned to an angle of 45^ for the face of the valve 
V. Around the outside of the top of 8 there is a screw ring X, 
Valve T, with its wings in the cylindrical part of 8, rests on the 
conical seat, and is held in place by the valve stem T, which fits 
loosely in the valve, as shown, the bottom of the stem being below 
the level of the valve seat. As will be noticed, the valve extends 
beyond the face in a sort of projecting lip, the size and shape ol 
which, as well as those of the upper face of the adjustable ring X, 
vary in the different designs of valves. The object and necessity 
of the lip and ring will now be explained. • 

Suppose F to be an ordinary valve with a conical face just 
covering the seat. The spring P, being under compression to 
resist a certain pressure, would allow the valve to rise only slightly 
for an instant when that pressure is reached, as the resistance of 

Digitized by 


BoiLEB Fittings 91 

the spring to still farther compression increases with the amount 
of that compression. The valve would, therefore, open and close 
continuously, discharging only a little steam each time. But, if 
the face of the valve is enlarged beyond the seat, it will be readily 
understood that, as soon as the valve opens to the pressure, the 
escaping steam acts on an increased area; therefore, the opening 
for the escape of steam is increased suddenly, and the valve 
*' pops '* and is held open imtil the pressure has fallen below the 
opening pressure. To prevent too great a drop in the pressure 
before the valve closes, or, in other words, to reduce the difference 
between the opening and closing pressures so that it shall not 
exceed 6 pounds, the adjustable ring X is provided in connec- 
tion with the deflecting lips. By means of this ring, the opening 
for the escape of the steam, after the latter has been deflected by 
the lip, can be slightly changed, and the closing pressure regulated. 

X in the Star valve, Plate XII, Fig. 1, is a screw ring with teeth 
on its outer circumference. By taking out the screw stop and 
inserting a pointed rod between the teeth, the ring can be screwed 
up or down. In the American valve, Plate XII, Fig. 2, the ring is 
not threaded, but is moved up and down by two screws, one of which 
is shown at N (the other one being diametrically opposite), which 
engage with the ring by means of collars. This arrangement is 
similar to the ordinary stuffing-box gland. • 

Lift of Valves. — It was stated above that the spring must be long 
enough to allow the valve to lift one-eighth of its diameter when 
set at the working pressure. This must not be mistaken for the 
actual distance that the valve lifts when blowing, as this rarely 
exceeds i". The area of the valve is calculated for a lift of only ^' 
when blowing at the full steaming power of the boiler. If the 
spring were short, so that it would allow only ^" or yV" movement 
and no more, it would soon become permanently set. But, by mak- 
ing the spring longer, so that the valve, say a 3" one, can lift one- 
eighth of 3", or f", the required yV" or 4" movement of the valve will 
be always within the elasticity of the spring. 

To guide the upper end of the valve when it lifts, the valve 
casting is extended in a cylindrical shape, which permits it to 
slide in the cylindrical bottom end of W. A liner K is shown in W 
in the cut of the Star valve, Plate XII, Fig. 1, which is not put in 
naval valves, as everything is of composition. 

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92 Mabinb and Natal Boilers 

Besetting Valves. — ^When a change is to be made in the opening 
or blow-off pressure of the valves on a boiler, the fires are put in 
such condition that the steam pressure can be easily raised to 
the blowing-off point for a few minutes at a time. The caps E 
are taken off by unlocking and removing the pins or keys I, J. 
These pins not only prevent tampering with the adjusting heads 
D, but secure the handle to the valve rtem. The details of the 
adjusting gear are not shown in the Star valve, and reference is 
therefore made to Plate XII, Fig. 2, but the description will answer 
for both. 

The lock nut J, on top of case W, is slacked off and the adjusting 
head D is set to the new pressure desired, by screwing down on it 
to increase, and screwing up to decrease the blowing-off pressure. 
The index R on the Star valve and the graduations on the stem of 
the American valve show the positions of D. 

The lock nut is now set up, and the steam pressure is allowed to 
rise for a short time so that the valves will blow or pop. Observe 
the opening and closing pressures by the steam gages on the boiler. 
If the valve does not reseat promptly (at about 5 poimds below lift- 
ing pressure), the ring X must be moved further away from the lip 
of the valve. Where there is more than one safety valve on a cham- 
ber, set one valve at a time, having the others " gagged *' while one 
is being set. 

Fig. Xllb is a gag. The hooks H, H are set imder the compres- 
sion nut, and the bolt B is screwed down on the top of the stem. 

When both opening and closing pressures have been satisfac- 
torily adjusted, secure the screw stops 0, in the Star valves and 
then replace caps E and the handles, and lock them in place. 

While it is preferable to set the valves by steam, it can also be 
done by filling the boiler with water, disconnecting^ the main escape 
pipe, and watching for the valve to lift as the pressure is put on 
from the main feed pump. 

Lifting Oear. — ^Besides the automatic lifting of the valves by 
steam pressure, mechanism is always fitted so that the valves can 
be raised by hand from the fire-room, or from a passageway outside 
of the fire-room, or from the deck above. The last two connections 
are emergency ones, for use in case of accident when it is impos- 
sible to work the valves from the fire-room. 

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Digitized by VjOOQIC 

BoiLEB Fittings 93 

Care and Overliatiling of Valves and Lifting Gear. — ^In order to 
ensure the proper working of the valves and the gear^ the Naval In- 
structions require that the hand lifting gear shall be thoroughly 
tested at least once each week^ whether the boiler is steaming or idle, 
and if the boiler is steaming, the valves shall be lifted weekly by 
steam pressure also. Should the gear work hard, the joints should 
at once be overhauled, cleaned and oiled. As a further precaution, 
these joints should be disconnected and thoroughly overhauled at 
least once in six months. The threads of the raising screw, being 
more liable to accumulation of coal dust, on account of the oil or 
tallow used to lubricate them, require particular attention. 

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Marine and Natal Boilebs 

IJteam Gages. — Each boiler has attached to it one or more gages 
by means of which the steam pressure is indicated. Fig. 55 shows 
one of the types usual in the U. S. Navy, with the screwed bezel, or 
front, the glass cover, and the dial removed. For boilers working 
at 160 to 180 pounds pressure per square inch, the dial is usually 

Fio. 55. 

graduated to 240 pounds. For higher pressures, the springs are 
stronger and the dial is graduated sometimes as high as 500 pounds. 
The double Bourdon spring S is made of seamless-drawn tubing, 
elliptical in section, and either plain or corrugated. The upper 
ends D, D are closed, and the lower ends open into the hollow socket 
0, which, at E, is connected by a pipe with the steam space of the 

Digitized by 


BoiLBK Fittings 95 

Base and top plates are secured to the mechanism support as 
shown. The pinion spindle, and the spindle of sector H, are held 
between these two plates. The pointer is held on the upper end of 
the pinion spindle with a friction fit. By the system of levers, one 
end of which is connected to the ends D, D of the spring 8, and the 
other to the toothed sector H, any motion of D is multiplied and 
transmitted to the pinion on the axis of the pointer and engaging 

The spring 8 being elliptical, with the longer diameter perpen- 
dicular to the curvature of the spring, any increase of pressure on 
the inside will tend to equalize the diameters of the ellipse, and thus 
cause each tube to straighten, tiiat is, move the closed ends away 
from each other. The diameters of the ellipse will tend to equalize, 
because any pressure inside the tube tends to make the tube take 
its greatest cross-sectional area, which, for a given length of per- 
iphery, is the circle. Any shape of cross-section, not a circle, would 
have the same effect, but it is apparent that the ellipse is most 
advantageous. This can be easily understood by folding a strip 
of paper on itself several times, closing one end and rolling up the 
folded paper. Blowing into the open end will straighten out the 
roll. The elasticity of the metal of the springs, if not exceeded, 
will bring the ends back to their normal position when the pressure 
is decreased. The hair-spring keeps the joints of the mechanism 
pulled in one direction, preventing lost motion. A small pin on the 
dial stops the pointer at a little above zero. The springs are of such 
shape and strength that no permanent set is acquired imder any 
pressure shown on the dial. All interior parts are made of non- 
corrosive materials, and the movement is made as light as possible. 
The casing is made of brass, nickel-plated. 

To prevent tlie ill effect of actual contact of the steam with the 
springs, all gages intended for steam must have a siphon fitted 
to them below E. The siphon is made by bending a complete 
circular loop in the pipe leading to the boiler. In order that it 
may be effective, the siphon is made sufficiently large to contain 
enough water to fill both springs when imder pressure, and so 
fitted that this water seal will not be drawn out of the siphon when 
the pressure is off. A small cock, by which the gage can be shut 
off, is fitted between the siphon and the gage. 

The dial is graduated for every 5 pounds by comparison with 
a mercurial column. To make sure that the boiler gages give 

Digitized by 


96 Marikb and Naval Boilbrb 

reliable indicationsy they must be tested at least quarterly on naval 
vessels by comparison with a standard gage, which is kept correct 
by frequent tests and is used only as a test gage. 

Q^Lge Cocks. — In addition to the water gages, each boiler or steam 
drum is fitted with several gage cocks, each attached independently 
and directly. In double-ended boilers, each end is fitted with these 
cocks. They are spaced equally in a vertical direction, about 6" 
in fire-tube and 3" in water-tube boilers, the lowest one in fire-tube 
boilers being about 4^^ below the highest heating surface. By opening 
each cock in succession, an experienced man can tell, from the 
steam or water blowing out, approximately where the water level 
is, and thus check the indications of the glass gages. These cocks 
are fitted with levers and rods, where necessary, to work them from 


Pio. 56. — Gage Cocks. 

the fire-room floor, and with a drip pan and a drain pipe leading to 

The gage cocks should be tested every watch, and at a time when 
the gage glass is known to give an accurate indication of the water 
level. The appearance and sound of the blast from each cock should 
be noted, and be used as criteria in case of subsequent failure of the 
gage glass. 

Fig. 56 shows a pattern used in our navy, il is a composition 
valve chamber which is screwed into the boiler or drum by the gas- 
pipe thread 8. The valve V, its spindle D and guide C are turned 
from one piece of rolled manganese bronze or Tobin's metal. The 
guide C is triangular in section, and the spindle D is circular where 
it passes through the movable seat B, and square at the end T. 
The valve has two faces. The inner seat for the valve is formed in 
the casting A, and the outer one in the block B, which can be 
screwed in and out by the handle H. 

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The valve is closed by screwing in B, and opened by the steam 
pressure when B is screwed out. The opening of the valve is at 
least f '^ in diameter^ and that of the discharge at X at least i". 
By a wrench at T, the valve can be turned and the passage around 
O be kept dear. The movable seat serves as a stuffing-box^ but in a 
more efficient and safer manner. 

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98 Marine and Naval Boilers 

Water-Oage Glaggcs. — These are fitted at the front, or more 
generally at the sides, of each fire-tube boiler, and on the side or 
head of each steam drum in water-tube boilers. Double-ended fire- 
tube boilers have two of these gages at the feeding end, placed as far 
apart as possible, and one at the other end. Fig. 57 shows a glass 

Fig. 57. 

water gage without the wire-mesh guard, which is often fitted 
around the glass. All water gages must be automatic or self-closing. 
The gage consists of an annealed glass tube, secured by stuflBng- 
boxes to the top and bottom shut-off cock or valve chambers, the 
blow-out cock or valve at the bottom, and an automatic self-closing 
valve in the back of each shut-oflf chamber. On water-tube boilers, 
the whole gage is connected directly to the nozzles on the steam 
drum, the shut-off cocks being then frequently placed back of the 

Digitized by 


BoiLBR Fittings 99 

self-closing valve. On fire-tube boilers^ the chambers are connected 
by pipes to the top and to near the bottom of the boiler, respectively, 
as in Plate I, each pipe having a stop valve on the boiler shell. 
From the blow-ont valve a drain pipe leads down to the bilge. 

The glass is |" in outside diameter for all large boilers, and 
f" for small boilers, the exposed length varying from 10" to 16". 
and the whole length from 2" to 2^" more. One or two rubber rings, 
or grommeU, around the glass near each end, set up by a washer 
and nut on each stuffing-box, make steam- and water-tight joints. 
These are shown at A, Fig. 67. 

To prevent scalding of the firemen when a gage glass breaks, 
automatic self-closing valves are fitted. These consist, as shown 
in Fig. 57, of a small valve or ball, which is free to move within a 
chamber through which the steam or water passes from the boiler to 
the glass. So long as there is equilibrium of pressure within the 
water gage, this automatic valve docs not move. But if the glass 
breaks, there will be a rush of steam and hot water into the fire- 
room, and, owing to the lower pressure on the opposite side, the valve 
will be forced against the seat provided. The amount of steam and 
water blown out will thus be very small, and the shut^oflE cocks or 
valves can be closed by hand without danger of scalding. A new 
glass can then be put in by slacking back the stuffing-box nuts. To 
catch any small pieces of glass, in case of breakage, a guard of wire 
gauze or heavy glass is often fitted around the glass. 

Fig. 67 shows the Star gage glass with " ball '' valves. The auto- 
matic valves are shown open ; the shut-off valves are open. It will 
be seen that there is a seat for the automatic valve and another one, 
opposite this, for the shut-off valve. The ball in the Star gage rolls 
down the slightly conical surface when in equilibrium. The stem 
of each shut-off valve ends in a pin projecting beyond its seat, by 
means of which the automatic valve is pushed back to its normal 
position as the shut-off valve is closed. When the glass has been 
renewed, the shut-off valves are opened, and the automatic valves 
remain in place and leave the passage for steam or water open. 

Where the water gages are too high above the fire-room floor, the 
wooden wheels are replaced by grooved metal ones, with knurled 
surfaces, which are worked from below by a continuous chain. 
When cocks are fitted, they are worked by levers and rods or chains, 
the latter hanging down to within easy reach. 

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Mabinb and Naval Boilers 



















Fio. 68. — Dewrance Mica-Lined Water-Gage Glass. 

Fig. 68 shows a Dewrance water-gage glass that is giving excellent 
results. This consists of two heavy outer frames A bolted to a 
center frame B. In recesses in the center and outer frames are 
secured two heavy glass plates, lined with a sheet of mica on the 
side next to the inner frame. These glasses are sufficiently far apart 
to allow a space for steam and water between them. All of the 

Digitized by 


Boium FiTTiNos 101 

water condensed in the tipper arm of the gage drops down on 
the surface of the water, making the level very conspicuous. A 
light, arranged to shine through the glass from behind, makes the 
water level more apparent The mica sheets protect the glass and 
are easily replaced; if the water wears away the mica and etches 
the glass, the glass can be ground and used again. The frame is 
heavy and rigidly supports the glass. This frame can be installed 
with any system of automatic water gages in the place of the glass 
in the water-gage stuffing-boxes. 

Numerous types of water-gage glasses have been used. The two 
described above, however, illustrate the principles involved. 

Looation of Water Gages. — ^The gage must be so placed that the 
water tender may know that there is a safe amount in the boiler, 
so long as the water shows in the glass, and the glass must' be long 
enough to show the level under all ordinary variations. 

On fire-tube boilers, the gage is placed at such height that the 
lowest exposed part of the glass is at least V above the top of the 
combustion chamber; the latter is usually shown by an indole plate 
fixed close to the water gage. The working water level is XU^U} 
from 6'' to 8" above the bottom of the exposed glass.. -On wat^r- 
tube boilers, the gages are so fitted that the middle of 4he glials, is 
either below or at the center line of the drum. 

Sometimes, instead of connecting the gages direct by pipes with 
the top and bottom of a fire-tube boiler, they are connected to a 
stand pipe, as in the English-built ^' Albany '' and " New Orleans.'* 
This pipe is a hollow casting consisting of a vertical part with two 
horizontal legs. The latter are connected direct to the boiler shell, 
without valves, the center of each opening in the shell and the 
corresponding shut-off cock of the gage being nearly in the same 
horizontal plane. The colunm of water in the stand pipe, being out- 
side of the boiler, and between it and the gage, is less exposed to the 
effects of rapid ebullition than the water inside the boiler. The 
indications of the gage will, therefore, be more reliable than if it 
were attached directly to the shell. The openings of the stand pipe 
are, however, too near the working level of the water, and any oily 
scum carried up with the steam will be more liable to get into and 
dirty the glass than if the gage were connected to the top of the 
boiler. When the boiler is forced much, the effects of the violent 
boiling of the water extend down to near the lower opening and 
cause unsteady indications in the gage. When the lower part of the 
gage is connected to the bottom of the boiler, where the water re- 

Digitized by 


102 Marinb and Naval Boilebs 

mains almost quiet under all rates of steaming, no such unsteadi- 
ness can occur. The method used in our navy is, therefore, 

Trying Oage Glasses and Cocks. — ^In order to make sure that the 
indication of the gage glass is correct, and to clear the glass and 
connecting pipes of oil or obstructions, the gage is tried frequently 
during a watch. The whole glass and upper pipe are blown through 
by closing the lower shut-ofE valve and opening the blow-out cock. 
Then, by closing the upper valve and opening the blow-out cock, 
the lower passage will be cleared. After these trials have been 
made, the water in the glass will resume its level quickly, if the 
glass is in working order. The gage cocks are then tried, and, if 
these indicate a serious difference, the glass must be blown through 
again. * It often happens that a piece of scale or other matter closes 
the opening in the lower pipe. In this case, the indication of the 
glass would be altogether unreliable, and, if the opening be not 
promptly cleared, would become dangerously misleading by the 
rapid increase in level due to cond^sation of steam from above. 
;"Et:tlie:top shut-off valve or the upper valve on a boiler under steam 
were closed, the glass would show full, as there would be no pressure 
•2bh^tfi6.Vajir in it. 

If, after blowing through several times, the glass does not work 
properly, the whole gage must be shut off by closing the stop valves 
on the boiler, the glass be drained, and then the shut-off valves be 
taken off. The automatic valve and part of the passages can then be 
examined and cleaned. If still unsatisfactory, the glass must be 
cleaned out and the grommets and passages below be overhauled. 

When trying the upper cock of a gage fitted to a stand pipe, a 
possible error may be made. Suppose the passage in the upper leg 
of the stand pipe to be choked. The glass would still be in commu- 
nication with the boiler through the vertical connecting part and 
the lower horizontal leg of the stand pipe. If now the upper shut- 
off cock is tried, as explained above, water would be forced up 
through the vertical part and down through the glass, thus seeming 
to indicate too much water in the boiler. As there are no valves 
between the boiler and stand pipe, the latter cannot be tried sepa- 
rately. To reduce the chances of their choking, the stand-pipe 
passages are made large, and the probability of the above error 
being made is, therefore, very small. 

Every water tender should blow through and test all the gage 
glasses and cocks on his boilers immediately after he comes on watch. 

Digitized by 


BoiLBB Fittings 103 

Effect of List on Boilers. — ^When a ship fitted with fire-tube boilers 
is injured in action or by accident^ so that she has a permanent 
list^ great care must be used to ascertain the proper working level 
for the altered position of the water in the boilers with reference 
to the highest heating surface. As stated before, double-ended 
fire-tube boilers have two water gages at one end and another at the 
other end. Single-ended boilers, placed fore-and-aft, have only two 
gages, both at the same end ; when placed athwartship, another gage 
is usually fitted at the back end. 

Take the case of the fire-tube boilers placed fore-and-aft and a 
list to port. So long as the list is small enough so that water 
shows in the starboard gage, no heating surface is uncovered. But 
if the starboard gage'^is empty, the port gage, which will probably 
be quite full, cannot be used to indicate the water level. The 
starboard gage must then be depended on, after the boilers have 
been pumped up to bring the water in sight in that gage. In the 
same way, with fire-tube boilers placed athwartship, the gage at the 
end showing the lower level must be used. In water-tube boilers, 
the placing of the boilers, as well as the arrangement of the drum, 
tubes and down-takes in relation to each other, will influence the 
circulation when the ship lists badly. In every case, the water level 
must be adjusted as well as possible to insure against the overheating 
of the exposed parts. 

If the ship is down by the head or stern, boilers placed athwart- 
ship will show comparatively little difference in level between 
the two front gages. If the boilers are fore-and-aft, the matter 
becomes more serious, especially with double-ended boilers. As 
before, so long as one of the end gages, the one showing the lower 
level,* can be depended on, the boiler may be worked with safety. 
But if there are front gages only, and these are full at the lowest 
safe working level, it will be unsafe to keep steam on the boilers. 

It will be noticed that the above explanations apply only when 
the ship has a permanent list. The ordinary changing of water 
level, as the ship rolls, requires no special attention, as the heating 
surfaces, even when uncovered by a deep roll, remain so for a short 
time only and are kept damp by the splash of the water. 

With water-tube boilers placed fore-and-aft, as they are generally, 
no trouble from the listing of the ship is likely. When placed 
athwartship, the circulation may be interfered with in some types 
having inclined tubes, if the list toward the high ends of the tubes 
is equal to or greater than the angle of inclination of the tubes. 

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104 Marine and Naval Boilebs 

Drain Cocks. — Drain cocks are placed in the lowest part of the 

boiler to drain all of the water out of it if desired. They are usually 

asbestos-packed cocks or ordinary heavy plug cocks worked by means 

of a socket wrench. 

Air Cock. — Each boiler is fitted with a small cock at the highest 

point of the shell or steam drum, to permit the escape of air when 

filling the boiler above the level of the gage cocks, and to show, 

by the escape of water, that the boiler is quite full. A copper 

drain pipe leads down to the bilge with its end in plain view, thus 

giving warning when the boiler is full and keeping the surplus 

water away from the boiler clothing. In some water-tube boilers, as 

was seen in Chapter III, parts of the tubes are higher than this 

cock and cannot, therefore, be kept entirely full of water, as in 

the Ohio type. 

Connection for Testing Water. 

— A small connection with a valve 

on it, usually an ordinary globe 

valve, is fitted to the cross box, or 

lower water drum, of water-tube 

boilers and to lower part of shell 

in fire-tube boilers for drawing 

water for test. In the older boilers 

this was connected to a salinom' 

eter pot in which the density of 

the water at a certain temperature 

was measured by means of a 

hydrometer bulb, graduated in 

densities at the temperature. In 

later boilers the salinometer pot 

was done away with, the end of 

the connection being kept free; 

the water was caught in a cup and 

the density was measured in the 

same way. Within the last few 

years the density measurements 

with the hydrometer have been 

discarded, and chemical tests are 

now made. 

Salinometer pots are still used 

on evaporators, and one is shown 

,, .« ^^ Fig. 69. 

FiQ. 59. ° 

The instrument usual in oiir 

Digitized by 


BoiLBB Fittings 105 

navy consists of the pot, formed by the two cylinders c and $, and 
the connecting channel d, the thermometer I and the hydrometer k. 
The pot shown here may be replaced by an ordinary^ deep handled 
pot, into which water is drawn ; the one described is, however^ much 
more convenient. 

Valve a is connected to a small pipe leading from the water 
space of the evaporator, near the bottom. A cock is put in this pipe 
80 that the evaporator can be shut off if the pipe should be broken. 
A is a drain cock for cylinder e. The thermometer is held in place 
by spring clips. The hydrometer k is of glass for ordinary use, 
there being a standard one of brass on each ship. It is a closed tube, 
enlarged in the middle to give buoyancy, with a lower bulb weighted 
with shot to make it float upright. A paper scale on the inside of 
the stem of the hydrometer gives the degree of concentration for 
three temperatures, 190^, 200*" and 210", of which the figure shows 
the first two. The scale is graduated to show the number of pounds 
and quarter pounds of salt contained in 32 pounds of the water to 
be tested. The average sea water is taken as containing 1/32 part 
of solid matter (D. K. Clark gives 1/30), and its density or concen- 
tration is represented by 1. The concentration of pure fresh water 
is, of course, zero, and is marked by F. W. 

The principle utilized in a hydrometer is that, when a body 
floats freely, the weight of the body is equal to that of the liquid 
displaced. The weight of .the hydrometer being constant, it fol- 
lows that it will sink further in fresh water than in the denser 
sea water. By noting the line of notation on the stem for various 
degrees of concentration at a given temperature, the scale for that 
temperature is obtained. For other temperatures, the scale varies 
about i of 1/32 for every 10" F., that is, the hydrometer will float 
higher in the cooler and, therefore, denser water. Hence, if the 
hydrometer has only one scale, which has been graduated at 200" F., 
and the temperature of the water in the pot is 190" when the read- 
ing of the hydrometer shows 2, the actual concentration would be 
24, while for a temperature of 210" it would be 1}. 

When the concentration, or saturation, as it is often called, is to 
be taken, the hydrometer is removed and valve a is opened. The 
water from the evaporators is forced into tube b, the end of which is 
closed by the cap 0, and finds its way through the small holes near 
the top, into the open cylinder c, and through d into e. Cylinder e 
is kept full to a convenient height by means of the overfiow pipe /, 

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Marine and Naval Boilers 

which takes off the surplus water. When the temperature of the 
water is falling, the hydrometer is put in, and the concentration is 
then read off on the scale corresponding to the temperature. 

The above instnmient does not measure the concentration very 
closely ; while it is suflBciently accurate for evaporators, more delicate 
tests, which can be made by chemical means only, are required for 

The ordinary nitrate of silver test for the purity of 
drinking water, made by the distillers, has been in use 
for a long time. Nitrate of silver has a strong afiSnity 
for chlorine, and as sea water contains sodium chloride 
or common salt (about 2.35^), and magnesium chloride 
(about .31^), it will attack these and form a milky-white 
precipitate. The slightest trace of chloride, although 
this may not be sufficient to be harmful, will thus be dis- 
covered in the water. But this test, as usually made on 
board ship, is not a quantitative one. To show the exact 
number of grains of chlorine in each gallon of water, 
some other chemical, which the nitrate of silver will not 
attack until all of the chlorides have been converted into 
silver chlorides, must be used. 

An exact method of measuring the grains of chlorine 
per IJ. S. gallon of water is described in the Appendix. 

Zinc Protecton. — ^Until recently, zinc protectors were 
used in boilers in the U. S. Navy, to prevent corrosion. 
They are still used in the boilers of tugs and vessels 
of the Navy manned by crews of the auxiliary service. 
When used, zincs must have direct, clean metallic con- 
nection to the boiler, as shown in Fig. 60. Provision 
must be made for collecting the particles of zinc as it decomposes, a 
basket, as shown at B in Fig. 60, serving this purpose. The satisfac- 
tory prevention of corrosion secured by the use of boiler compound, a 
mixture consisting, for the most part, of sodium carbonate and of 
other chemicals, has made unnecessary the use of zinc protectors in 
boilers, where the degree of alkalinity of the water can be determined 
with regularity and accuracy and be maintained within a prescribed 

Tube Cleaning Connections. — For blowing soot off the tubes, con- 
nections are made to the auxiliary steam line and to the fire-room 
pneumatic line for hose connections; steam or air may be used. 

Fio. 60. 

Method of 



Digitized by 


BoiLKR Fittings 107 

Cleaning and dusting doors are placed in the boiler casings through 
which an air or steam lance may be inserted between the rows of 
tubes or headers and the soot blown from the tubes. 

Swash plates are placed in the steam drums below the water level ; 
they are run at right angles to the axis of the drum and prevent the 
water from surging from one end of the drum to the other. 

In some types of boilers swash plates are placed so as to direct 
the incoming feed water to the outer rows of tubes or to the down- 

Beposit pans are shallow pans placed under the internal feed 
pipes to catch any sediment^ scale or grease that may be brought 
into the drum in the feed water. 

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Boiler accessories will now be described with particular reference 
to those found in a marine boiler plant. They are, in general terms, 
as follows : 

1. Feed accessories, those having to do with maintaining the 
water at the proper level in the boiler. 

2. Steam accessories, those having to do with conveying the 
steam from the boiler to the steam engines and delivering it ready 
for use. 

3. Firing accessories, those having to do with placing the fuel on 
the grate, working the fires, and removing the ashes, soot and scale. 

4. Testing accessories, those testing outfits necessary around a 
properly equipped boiler, installed for measuring or testing the 
qualities of the steam, water and fuel. 

5. Miscellaneous accessories. 

1. The feed accessories are: 

Feed and filter tanks. 

Reserve feed tanks. 

Feed suction pipes. 

Feed discharge pipes. .^ 


Feed pumps. 

Automatic controllers for feed pumps. 

Air chambers. 

Grease extractors. 

Feed-water heaters. 

Air extractor. 

Automatic feed regulators. 

2. Steam Piping and Accessories: 

Main and auxiliary steam pipes. 

Expansion joints. 

Pipes passing through water-tight bulkheads. 


Steam traps. 

Reducing valves. 

Escape pipes. 

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Boiler Accbssoribs 109 

3. Kring Accessories: 

(a) For Coal-^nd-Oil'Buming Boilers: 

Tools and appliances for handling ashes and soot. 
Tube cleaners and scrapers. 
Forced-draft blowers. 

(b) For Coal-Burning Boilers Only (additional to (a)). 

Firing tools. 
Time-firing device. 

(c) For LiquidrFuel-Buming Boilers Only. 

Pipings tanks and pumps in general. 

Duplex oil service pumps. 

Hand pumps. 

Pressure oil heaters. 

Oil strainers. 

Oil burners. 

Air registers. 


Heating coils. 

Automatic stop valves. 


4. Testing Accessories (see Appendix) . 

5. Miscellaneous Accessories: 

Whistles and sirens. 
Calking tools. 
Tube expanders. 
Safety-valve gags. 


Peed Water. — ^Though generally considered as belonging to. a 
study of marine engines, condensers and evaporator plants are prop- 
erly boiler accessories. With the high' steam pressures now carried 
in water-tube boilers, distilled or condensed water is an absolute 
necessity. Water obtained from on shore, while fresh and neutral, 
may contain scale-forming ingredients, or ingredients that break 
down, under high temperatures, into acids which attack the boiler 
materials. Scale deposited from the water on the metal of the 
boiler causes overheating, and consequent weakening of the metal. 
Acids formed eat away the metal, reducing its thickness, and hence 

* Not fitted on boilers burning oil only. 

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110 Marine and Naval Boilebs 

I its strength. The higher the steam pressure the higher the tempera- 
Iture. Therefore, the higher the pressure the more Kable is the 
boiler to deteriorate and to rupture when there are impurities in 
the water. 

While it is the practice to obtain water from on shore for filling 
boilers and tanks, it would be safer to use only distilled water for 
this purpose, as some shore waters are more injurious, both in 
causing corrosion and formation of scale, than sea water. 

Condensers are ai necessary boiler accessory, not only becauBe they 
render the heat engine more eflScient, but because they save for 
boiler feed water the steam used by the engine. Owing to the 
fact that only a limited supply of make-up feed water can be car- 
ried on a ship, evaporators are necessary boiler accessories, to re- 
place the feed water lost through leakage or any other cause. As 
almost all boiler troubles come from using unsuitable feed water, 
efficient management of condenser and evaporator plants is neces- 
sary to an efficient boiler plant. 

For the reasons given above, condensers and evaporators should 
properly be included in a treatise on boilers ; as they are included, 
however, in the text-book on marine engines U3ed at the Naval 
Academy, they will not be described here. 

Feed and Filter Tanks. — After passing through the condenser the 
water is drawn out by the air pump and is discharged into the filter 
compartment of a combined feed and filter tank, located near the air 
pump in each engine-room. The filter compartment is separated 
from the feed tank proper by a horizontal plate and is divided into 
chambers by vertical plates, alternately secured to the compartment 
top and bottom. The arrangement of these plates requires the water 
to follow a circuitous route through the chambers and the filtering 
material, loofa sponges, or bags of excelsior or charcoal, or burlap. 

The feed and filter tanks are connected one to the other by a cross- 
connecting pipe. From this pipe lead the independent suction pipes 
to the main feed pumps and the auxiliary feed-pump suction main, 
the latter supplying the several auxiliary feed pumps in the fire- 
rooms. Besides this pipe there are the following connections and 
fittings : 

(a) To filter compartment: (b) To feed tank: 

1. Air-pump discharge pipes. 1. Vapor pipe. 

2. Vapor pipe, to atmoephere. 2. Overflow pipe. 

3. Dynamo air-pump discharge 3. Trap discharge main. 

pipe. 4. Drain cock. 

4. Distiller fresh-water pipe. 5. Gage glass. 

5. Trap drains. 6. Graduated measuring scale. 

6. By-pass pipes from fllter to 7. Thermometer. 

feed tank. 8. Zinc protectors. 

9. Alkaline solution tank. 
10. Clothing and lagging. 

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Reserve Feed Tanks.— Some double-bottom compartments are 
designed for this pnjpose. They have suction and filling pipes lead- 
ing to an auxiliary feed-pump suction manifold. They can be filled 
through this manifold from a connection on the ship^s side or from 
the distiller fresh-water main. Other leads from this manifold are 
to: (1) Main feed pump direct; (2) auxiliary feed-pump suction 
main; and (3) main condensers direct. All reserve feed tanks are 
connected to a discharge manifold of one of the auxiliary feed pujnps 
in such a manner that they can be emptied from one to the other. 
They are provided with sounding tubes for measuring the amount of 
water contained^ air escapes, and manholes for access. 

Feed Suction Pipes. — The main and auxiliary feed-pump suction 
pipes are connected to the feed tank cross-connecting pipe, tiie auxil- 
iary feed-pump pipe being in one engine-room only. Sometimes inde- 
pendent feed-suction pipes lead from the feed tanks to stop valves on 
the suction side of main feed pumps in each engine-room. The auxil- 
iary feed-pump suction pipe connects to all the auxiliary feed pumps. 

Feed Discharge Pipes. — The main feed pumps in each engine- 
room discharge into a pipe leading forward. This pipe discharges 
through or can be bypassed around the feed-water heater and grease 
extractor. The pipes from the engine-rooms connect in the after 
fire-room and form a common main leading forward to the boilers. 
It has branches and valves so arranged that any main feed pump can 
feed any one or all of the boilers. The auxiliary feed pumps dis- 
charge into an athwartship pipe having branches through which it 
may discharge into any boiler in its own compartment and into the 
main feed discharge pipe. Gate or ^* straight-away ^' valves are em- 
ployed on these pipes. 

Any boiler can be fed from any main or auxiliary feed pump 
through either its main or auxiliary feed stop and check valves. 

All feed suction and discharge pipes are made of seamless drawn 
copper, with composition flanges brazed on. The end of the pipe is 
beaded into a recess in the face of the flange. 

Valves in the feed suction and discharge pipes are generally 
gate valves, with the exception of the boiler feed stop and check 

Digitized by 



Marine and Naval Boilers 

A gate valve of the type made by the Nelson Valve Company is 
shown in Fig. 61. This valve has a bypass, as shown at A, in order 
that the pressure may be equalized on both sides of the valve and the 
valve be opened easily. There are many types of gate valves in use, 

Fig. 61. — Gate Valve with Bypass. 

but this one shows the principles involved. This valve consists of 
parts as enumerated below in tabular form : 

1. Valve body. 6. Valve discs. 

2. Valve bonnet. 7. Valve disc, removable face. 

3. Valve gland. 8. Valve disc wedge. 

4. Valve stem. 9. Eemovable valve seats. 
6. Hand wheel and nut. 

Digitized by 



The body and bonnet 1 and 2 are made of composition^ iron or 
Bteel. The other parts are of composition ; 7 and 9 are made of a 
specially hard^ close-grained composition or Monel metal. Gate 
valves, when wide open, cause no obstruction to the flow of the 
water and there is no loss of head in passing through them, except 
that due to friction. They are called straight-away valves by some 

Feed Pumps. — There are three types of feed pumps in general 
use (the classification is made entirely with regard to the water end 
of the pump) : (1) The piston, (2) the plunger and (3) the tur- 
bine type. 

1. The piston pump, shown in Plate XIII, is of the Blake vertical 
simplex type, and consists of parts as given in tabular form along- 
side of the sketch. The water end of types 1 and 2 will be de- 
scribed ; the steam end may be the same for each. 

The pump piston rod 41 is secured rigidly to the steam piston 
rod 40, in the cross-head 31, and enters the pump cylinder 46 
through stuffing-box in upper pump head 49. The lower end of the 
pump rod is tapered with a shoulder at the upper end and a 
threaded portion at the lower end of the taper. The pump piston 
head 51 has a tapered hole through its central part in which the 
taper end of the pump rod fits. The piston head is held against the 
shoulder on the rod by nut 43 and lock nut 44. The piston head is 
made a water-tight fit in the pump cylinder liner 47 by fibrous 
or metallic packing rings, held in place in the piston head by the 
follower 62. The packing is held out against the cylinder liner 
by the segment ring 53 and set-out bolts 64, secured by lock pins 65. 
The pump piston head is slightly less in diameter than the cylinder 
liner. is the main suction pipe connected to the two suction 
chambers A and A' {A' is not shown) through suction valves 60. 
The chamber A for the top and A' for the bottom of the pump 
cylinder are separated by a diaphragm 78. B is the main discharge 
pipe, which is connected to both suction chambers through the dis 
charge valve seats 61. The action of the pump is as follows : On the 
down stroke the piston creates a vacuum in the upper part of the 
cylinder, above the piston. The vacuum created opens the suction 
valves, and the pressure in the discharge line keeps the discharge 
valves closed. Below the piston on the down stroke water is being 
forced out through suction chamber A' (in rear of 4) and through 
the discharge valves into discharge pipe B. The pressure created in 

Digitized by 


114 Marikb and Naval Boilebs 

the suction chamber on top of the suction valves keeps them closed, 
while it opens the discharge valves as it acts imderneath them. On 
the up stroke the vacuum in the bottom of the cylinder opens the 
suction valves in suction chamber A\ filling it and the bottom of 
the cylinder ; above the piston on the up stroke the pressure closes 
the suction valves in A and forces the water out through the dis- 
charge valves (seats marked 61) into the discharge pipe B, The 
pump therefore discharges once each stroke, and is called a double- 
acting pump. The suction and discharge valves are flat-seated 
metallic valves with removable composition seats. They ride on the 
valve stems 66, which, are seated at their lower ends on the suction- 
valve seats 61. The stems pass through the center of the discharge 
valves and seats and are secured at their upper ends by plugs 64, 
screwed into the pump body and covered with acorn nuts 65. The 
valves are held on their seats by the tension of light composition 
springs 68, secured in place aroimd the stems by suction guards 62 
and discharge guards 63. These valves are examined by removal 
of the valve chest cover 48. They are renewed by removing the plug 
and withdrawing the stem. The valves can then be removed or 
replaced through the opening made by the removal of the valve-chest 
cover. To examine or renew the pump piston packing, move piston 
to end of up stroke, then take off water-cylinder head and block it 
up against the cross-head. The follower can then be removed and 
the packing be examined or renewed. 

All feed pumps are fitted with a water-pressure gage to show the 
pressure of the water in the discharge pipe, and with a water- 
discharge check valve in the discharge pipe near the pump. Leaky 
piston packing is indicated by a drop in the discharge pressure below 
the normal pressure for a given speed of tlie pvmip. The amount 
of leakage may be determined by closing the water discharge valves 
and nmning the pump at a speed that will keep the pressure the 
same as when the discharge valve is open and the pump is working 
normally. By comparing the times for a double stroke when the 
discharge valve is opened and closed, the percentage of leakage per 
double stroke can be obtained. 

2. The outside-packed-plunger pump of the Blake type, shown in 
Plate XIII, Fig. 2, is what is called the vertical simplex center- 
pticked'plunger fned pump. In this the pump cylinder is divided 

Digitized by 


Boiler Accbssoribs 115 

into two parts, each part having its suction chamber and suction 
and discharge valves similar to the piston pump. The pump rod 
enters the head of the upper cylinder through a stuffing-box, and 
is secured to the plunger on the inside of tiiis upper cylinder. Thf 
plunger extends into each cylinder. The openings in the lower end 
of the upper part and the upper end of the lower part of the cylinder 
are made water-tight around the plunger by the plunger packing 
A, A. Any leaks around the plunger are always visible from the 
outside and can be stopped either by setting up on the gland nuts 
or by renewing the plimger packing, either of which can be done 
without taking the pump apart. This pump is double-acting. 

Plate XIII, Fig. 2a, shows the action of the water end of this 
pump when the plunger is making the down stroke, 

3. The turbine pump, shown in Plate XIII, Fig. 3, is a two- 
stage Worthington standard turbine pump. Turbine pumps are 
driven by steam turbines, electric motors or high-speed steam en- 
gines. The shaft 10 is connected to the motive power at its rights 
hand end, passes through the pump-casing stuffing-boxes at 14 and 
20, and has a thrust bearing at its other end. Two impellers 
6, 6 are mounted on this shaft and are secured to it by a key. The 
shaft is reduced in diameter, and the right impeller fits against the 
shoulder, while the other impeller is held against a distance piece by 
a nut 28 on the shaft. The water is drawn through the suction 2 to 
the center of the impeller; it is thrown out by the centrifugal action of 
the impeller blades through the diffusion vanes 3 and 4 into the 
annular chamher 1. In the diffusion vanes the kinetic energy of the 
water in motion is converted into the potential energy of water under 
static head. The pressure having been increased by its passage 
through the first stage, the water is now led from the annular casing 
between the division plates 6 to the center of the second impeller, 
where it is again thrown out through the second set of diffusion 
vanes 3' and 4' and out through discharge 1', and its pressure again 
increased. As the one shown is a two-stage pump, it will be seen 
that the water is discharged imder pressure from the second-stage 
annular chamber. The pumps are made with as many stages as are 
necessary to give the desired pressure at the discharge from the last 
annular chamber ; pressures have been carried as high as 900 pounds 
per square inch. 

Digitized by 


116 Marinb and Naval Boileus 

Automatic Control of Feed Famps. — Feed pumps are now gen- 
erally fitted with some form of automatic control that will maintain 
the pressure in the discharge pipe at the pressure for which the 
control is set. 

Fig. 62 shows one form of an automatic control valve. 

The steam, after passing the steam valve disc 1, acts on the under 
side of differential plunger 3. The valve stems 2 and 4 are screwed 

Pig. 62. — Automatic Regulating Throttle Valve for Feed Pump. 

1. Steam valve disc. 6. Yoke. 

2. Valve stem. 6. Valve-stem sleeve and wheel. 

3. Differential plunger. 7. Water space. 

4. Stem of differential plunger. 8. Leak-off space. 

into 3, and any movement of 3 is transmitted to valve 1. Valve stem 
4 slides in a loose fit in sleeve 6, which is turned by the hand wheel. 
Sleeve 6 works in a thread in yoke 5. The water space 7 is con- 

Digitized by 



nected to the discharge chamber of the water end of the pmnp. The 
areas of the top and bottom faces of 3 are so proportioned as to 
maintain the pressure in the feed-pump discharge greater than the 
pressure in the steam line by a certain ratio. 

When the demand for water in the fire-room is great, as when 
several check valves are open at the same time, the pressure in the 
feed discharge line drops, relieving the pressure in 7, and the steam 
in the valve casing, acting on the lower face of 3, opens the valve 
and the pump speeds up. When the demand for feed water is light, 
the pressure in the feed discharge line builds up and the increased 
pressure, acting on the upper face of 3,. closes the valve and slows 
the pump. The leak-oflE space 8 has a drain pipe to carry away any 
leakage from either the water space 7 or the steam space of the 
valve casing. 

Digitized by 


118 Marine and Naval Boilebs 

/v^gr A 


Pia. 62a.— Mason Pump Regulator. 

Digitized by 


Boiler Accbssobixs 119 

The Mason Pump Begnilator, Pig. 62a, is another pump regulator 
of good design. Its principal advantages are : accessibility of adjust- 
ing nuts, and arrangement of movement of piston valve and lever, 
one to two, so. that the spring resistance required is only one-half 
that of a direct spring on the valve stem. This enables a more 
resilient spring to be employed which results in a more sensitive 
action. The plunger is packed with Queen's packing, a patented 
article, formed to 8hai)e, and of special material to resist oil. This 
packing is self-setting. The operation of the regulator is as follows : 
Steam enters at A, passes around the balanced valve Y and leaves 
at B, The pump discharge is connected through a pipe to the 
bottom of the plunger cylinder. As pressure builds up in tlie pump 
discharge line the plunger lifts against lever F, overcomes compres- 
sion of spring, and through valve stem G closes valve 7. As pres- 
sure in discharge line falls, compression of spring pulls down lever 
opening valve Y. The compression of the spring is regulated by the 
adjusting nuts E, 

Air Chambers. — Feed pumps should have vacuum chambers on 
the suction line, as they provide a imif orm flow of water to the pump 
and make it run smoothly. 

Air chambers on the discharge line tend to cause a steady flow of 
water and to reduce the poimding of the pump at high speeds, by 
the cushioning effect of the air contained in them. The air 
chambers on the discharge side should have from 2 to 3^ times 
the volume of the. piston or plimger displacement. The vacuum 
chambers should be from 1 to 1^ times the piston displacement, and 
should be placed so as to receive the impact of the column of water 
in the suction pipe. 

Feed pumps are fitted with a connection from the discharge to 
the suction chamber in which a spring-loaded relief valve is installed, 
so that in case all feed check valves in the fire-rooms are closed at 
once and the automatic control valve fails to operate, the excess 
pressure will open the relief valve and bypass the water to the 
suction side. The automatic control valve is generally designed to 
maintain a pressure in the feed discharge line at least 50 poimds 
greater than boiler pressure; the relief valves are set to relieve at 
about 100 pounds greater than boiler pressure. 

Grease Extractor. — The feed suction line from the feed tanks to 
the main feed pumps is sometimes fitted with a greasB extractor. 

Digitized by 


120 Mabine and Naval Boilbrs 

The grease extractor used in the navy is composed of a casing 
and a perforated cartridge covered with linen or toweling and filled 
with loofa sponges. The water enters the casing and finds its way 
through the filtering material^ then passes through the cartridge to 
the main feed suction pipe.. This extractor should be installed 
double, so that one can be in use while the other is being cleaned. 
Where there is much grease in the feed water^ the extractor, where 
installed singly, can be bypassed while it is being cleaned. 

Feed- Water Heaters. — Where feed-water heaters are installed in 
the feed suction lines, they are called low-pressure heaters; when 
these are used, an additional pump is required to pump the water 
from the feed tank through the grease extractor and feed heater 
(either or both of which can be bypassed) into the feed suction 
lines. The pressure generally carried in low-pressure heaters is 
not over 20 pounds on the water side; and the temperature of the 
feed is limited to the highest that the feed pvmip will lift. With 
heaters of this type, the temperature can never be carried over 
200** P., and with the average feed pump about 180"* F. is the limit. 
The limiting temperature of the water which the feed pump will 
lift is due to the reduction in pressure on the suction stroke which 
must take place in order that the pump may lift the hot water. 
When the pressure is reduced a certain amount, the water will boil 
and the pump will lift steam instead pf water. 

Feed heaters in the feed discharge lines are called high-pressure 
heaters; their heads and tubes are tested to 550 pounds and their 
shells to 75 pounds pressure. The water in Jboth the high- and 
low-pressure types passes through the tubes and exhaust steam sur- 
rounds them. 

When using exhaust steam to heat feed water, it has been found, 
both by theoretical calcidations and by practical tests, that for every 
10® F. rise in temperature of feed water there is a 1^ reduction in 
the amount of heat necessary to produce the steam, with a corre- 
sponding reduction in fuel used. 

The temperature of the feed water leaving a high-pressure heater 
should be within 10** of the temperature of the exhaust steam. The 
navy requirements are that the exhaust steam should not be over 
10 poimds per gage or 25 pounds absolute. The temperature of 
steam at this pressure is 240** F., and the temperature of the feed 
can be carried to within 2° F. of the steam. A vessel having a high- 
pressure heater should be from 3i^ to 4j< more efficient than a sister 

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Boiler Accbssoribs 121 

vessel having a low-pressure heater and steaming in the same squad- 
ron. The feed-water heaters used in the navy are: (1) The 
straight flow, (2) the U-tube, (3) the coU and (4) the film. 

The straight-flow heaters are very similar to a condenser, and 
consist of a cylindrical shell filled with tubes. The tubes are ex- 
panded into the tube sheets. The shell has a water head at each 
end, one of which is divided. The feed water enters one chamber 
of this head, goes through a part of the tubes to the other head, then 
back through the other part of the tubes to the second chamber of 
the head to the discharge line. The exhaust steam surrounds the 
tubes in the shell; one tube sheet is connected to the shell by a 
method which allows for the expansion of the tubes. 

Tube Setarders. — Secently there has come into use with straight- 
flow heaters a device known as the tube retarder. This device is a 
flat strip of brass twisted into spiral loops at regular intervals along 
its length, inserted in the tube and firmly secured at one end. The 
retarder extends the entire length of the tube and agitates and 
checks the flow of the water. The retarders increase the efficiency 
slightly, by increasing the agitation of the water and breaking up 
the water 61m inside the tubes. 

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Marine and Naval Boilers 

In the TJ-tube heater, shown in Fig. 63, designed by the Bureau 
of Steam Engineering, the tubes D are bent into U-shape and ex- 
panded into the tube sheet C. The feed water enters through the 
opening E, and passes through the tubes, and out to the feed dis- 
charge line through the opening F. Exhaust steam enters the casing 
/4 at JJ and leaves through on the imder side of the casing. If 
tliis heater is placed with the tubes in the vertical plane, the exhaust 

FiQ. 63. 

steam enters at an opening K (top) and is drained out at J 

In coil heaters the water is forced into manifolds placed near 
the bottom of the shell, then through copper coils to a manifold 
near the top of the shell, then out to the feed line. The coils are 
secured to the manifolds in different ways, generally with cone or 
screwed joints, or ground-joint imions. 

The Schutte-Koerting Film Heater, shown in Plate XIV, is of the 
type installed in the U. S. Navy. The circulation of the water 
and steam is as shown. The water enters first into the lower half 

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of the main header A, passes into the outer copper tube and around 
the inner copper tube^ and then enters header B. From header 
B it flows back through the outer tubes and aroimd the inner tubes 
in the upper half of the heater to the upper half of header A, and 
thence to the feed line. The diaphragm D, separating the header 
into two compartments^ is corrugated to give stiffness and to allow 
for expansion. The tubes, two sets of which are shown and the 
others of which are indicated by the center-lines^ are spirally corru- 
gated for increased strength and heating surface. The corrugations 
are spiral, to give increased agitation to the water as it passes 
through the heater. It has been found that the passage between the 
inner and outer tube must be at least ^", in order that the tubes 
may not foul each other on account of imequal or irregular expan- 
sion. The inner tubes are .083" and the outer tubes .096" thick. 
The details of the joints of the tubes and headers are shown at 0, 
K and M. A number of stay-bplts, S, support the fiat parts of the 
headers. A number of feet not shown project from the periphery 
of B and keep it centered in the shell. It will be seen that the 
header B is free to move back and forth when the tubes expand 
and contract. 

Plate XV shows the Beilly Hultlcoil Feed Heater as installed on 
the U. S. S. Nevada. The shell, 8, is of steel plate. Water enters 
the lower manifold M, from which it passes through a number (in 
this case 52) of copper coils K to the upper manifold, and thence 
to the feed discharge line. The manifold is shown in A and B. 
The particular advantage of this heater lies in the absence of 
gaskets, which, in the U-tube and straight-flow types, make it 
very diflBcuIt to keep the joints of the heads tight. The method 
of securing the coils to the manifolds is shown at D and E» 

The end of coil K is turned into a mushroom as shown, and is 
held tight against the ferrule F by the coil nut N, which fits over 
end a of the projection on the manifold M, 

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Mabinb and Nayal Boilbbs 

Air Extractors. — On the latest ships in the U. S. Navy^ air ex- 
tractors. Fig. 65^ are installed in the highest parts of the feed dis- 
charge lines near the boilers. Air collects in the air chamber of the 
extractor and is blown off through the blow-off pipe. The action of 
the extractor is similar to that of radiators in the highest parts of 
steam and hot-water heating systems of buildings. Air collects in 
these high radiators from the system below^ and must be blown off 
through a pet-cock before the radiator will become hot. This 
example also illustrates the low heat conductivity of air. It is 

Pio. 66. — ^Alr Extractor. 

desirable to remove as much air as possible from the water before it 
enters the boilers, because the oxygen in the air is the most potent 
factor in the corrosion of the boiler metal. 

Automatic Feed Regulators. — ^Automatic feed regulators are used 
extensively in some foreign navies and in the merchant marine. 
The principle employed is that of stopping the feed into the boiler 
when the water has reached a certain level in the drum. The con- 
trivance for regulating the water supply to the boiler is fitted in 
the steam drum. While the automatic feed water regulator has 
been used to a limited extent in the XT. S. Navy, its reliability has 
always been questioned and it is not now installed. 

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Boiler Accbssoribs 126 


The feed water has been traced from the condenser to the boiler. 
The steam will now be followed from the boiler stop valves to the 
place where it is to be used. 

The general plan is to have two systems of main steam piping 
symmetrically placed on each side of the ship. On water-tube 
boilers there is only one steam stop valve. In some cases the main 
steam line is connected to the boiler through the auxiliary steam 
line, and in others the auxiliary steam line is taken from the main 
line, the main line being directly connected to the boiler stop valve. 

On the latest vessels, when superheaters are fitted, the boilers are 
directly connected to the main steam lines, the connection being so 
arranged that the steam can be either sent through the superheater 
or bypassed to the main line. The branches from the main steam 
line to the boilers are all of the same diameter ; the main steam line 
increases in diameter from the forward boilers aft, at each succes- 
sive connection. Stop valves, called cut-out valves, are placed in 
the main steam line at intervals in such a way that sections of boilers, 
or sections of the main steam line, can be cut 8ut as may be neces- 
sary. Just forward of the main engine throttle valves the main 
engine stop valves are placed. Main steam line stop valves are 
geared so that they may be operated from the deck above. 

The stop valves in the main and auxiliary steam lines are screw- 
down globe valves with flat valve seats. A bypass controlled by a 
small valve connects the steam spaces on each side of the larger 
valve. In the forward part of the engine-rooms the steam lines are 
connected to each other by an athwartship connecting pipe, having a 
stop valve at each end. The forward ends of the main steam pipes 
are connected by a loop of pipe that runs across the ship in the 
forward fire-rooms. This loop forms the forward part of the 
auxiliary steam line; branch pipes run from it to the various 
machines forward. In the same manner a loop connects the after 
ends of the port and starboard main steam lines, crossing in the 
after part of the engine-rooms. These loops forward and aft take 
the place of the auxiliary steam line and branches lead from the 
loops to the various machines forward and aft. Each main steam 
line has a pipe, called a " bleeder/' leading to the condenser. This 


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126 Marine and Naval Boilers 

pipe removes live steam from the lines when it is desirable to care for 
surplus steam which otherwise would escape by the boiler safety 

In each fire-room the port and starboard main steam lines are 
connected by athwartship pipes which have valves at each end near 
the main steam pipe. In the latest ships the evaporator steam 
supply is generally taken from the main steam line in one of the 
fire-rooms. Main steam lines are given a slope toward the boilers 
or toward the separators so the condensed water will run to one of 
these. Low places in all steam lines or valves, where water can 
collect^ are drained to automatic traps. 

All steam pipes 2^^ in diameter and above, and all pipes that carry 
superheated steam are made of seamless-drawn steel. Pipes^ less 
than 2" in diameter, not subjected to superheated steam, are made 
of copper. All exhaust piping is made of copper, that of 10-inch 
diameter and less being seamless drawn. All flanges for steel pipes 
are of forged steel; the pipes are expanded into the flanges and the 
end of the pipe is beaded over to fit a recess and be flush with the face 
of the flange. Flanges on superheated steam pipes are plain-faced, 
and the joints between these flanges are made up with a thin wash of 
boiled linseed oil. All steam pipe flanges are faced and grooved, and 
the joints are made with case-hardened corrugated copper gaskets. 
Exhaust steam pipe joints are made with fiber gaskets. 

Expansion joints are placed in steam piping, main and auxiliary, 
wherever there are not bends in the piping sufficient to allow for the 
expansion. The pipes are rigidly secured to the ship's structure at 
certain intervals, and are said to be anchored at these points. 
Wherever the pipe runs straight between two successive anchorages, 
expansion joints are placed. The rigid part of the expansion joint 
is generally anchored at or near the after bulkhead of each compart- 
ment, the pipes passing through stuffing-boxes in the bulkheads. 
In small pipns U-bends are placed to take up the expansion; they 
are placed near the center of the compartment, and the pipe is an- 
chored at each bulkhead. The weight of the pipes is carried by 
supports through which the pipe can expand. These supports are 
sometimes ri\eted to bulkheads and sometimes swing from the 
beams overhead. 

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Pig. 66 shows an expansion joint as generally fitted in naval 

A is the stuflRng-box casting, generally anchored to the ship's 
structure ; F is the gland, with its studs screwed into flange X and 
nuts outside of the gland by which the packing in 8 is adjusted and 
by which the joint around the sliding pipe P is made steam-tight. 
One end of the steam pipe is shown with its flange Z bolted to 
the flange Y on P; the other end of the main is similarly flanged 
and bolted to the flange K at the opposite end of il. To prevent the 
sliding pipe P from drawing out of A, T-headed stop bolts B are 
fitted between flanges X and Y. Bolts B slide through holes in 
flange X with a loose fit, the T-head being placed on the right side 
of flange X, 

Fio. 66. 

In some expansion joints there are nuts on both sides of the 
flange X; the one on the right side is adjusted to be just clear of 
the face of X with the pipe cold, and that on the left of Z to be 
just clear of X with the maximum steam pressure in C; the nuts 
at flanges Y and Z are set up hard against faces of flanges. 

Expansion joints exposed to superheated steam are made of cast 
steel, those not exposed to superheated steam are made of either 
cast steel or composition. The glands are made of composition. 
Expansion joints are fitted to all steam, exhaust and feed piping 
where there are not ample bends to provide for the expansion. 
Where there are ample bends and no expansion joints are fitted, the 
pipes are so fitted as to put them under tension when cold. 

Pipes Passing through Water-tight Bulkheads.— Steam, exhaust 
and feed piping are passed through water-tight bulkheads in one 
of the following three ways : 

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128 Mabine and Natal Boilsrs 

1. When the pipe is anchored to the bulkhead, the flange on one 
section of the pipe is about one and one-quarter times the diameter 
of the standard flange for that size of pipe, and has two rows of bolt 
holes in it. This flange is bolted to the bulkheads through the 
outer row, and to the standard flange of the other section through 
the inner row of bolt holes. 

2. When the pipe is not anchored to the bulkhead, but has a slid- 
ing motion through it, the joint in the bulkhead is made tight with 
a stuffing-box. 

3. When the bulkhead is adjacent to or part of a magazine, to 
prevent the heat from being conducted from pipe to bulkhead a 
casting with an annular chamber in it is fitted to the bulkhead 
around the pipe. Water circulation is kept up in the annular 
chamber by a pimap. 

Separators. — To remove water from steam pipes, all pockets and 
places in pipes or valves where water can collect are connected by 
drain pipes to automatic traps. As an additional precaution, where 
the motive power is a high-speed reciprocating engine or turbine, 
separators are fitted in the steam lines in the engine-rooms near 
the throttle or controlling valves. 

The function of the separator is to collect such water as is not 
taken care of by the traps and drains, and run the water so collected 
directly to the feed tanks, thereby avoiding the danger in allowing 
water to go through a high-speed reciprocating engine or turbine. 
The separation of water and steam is effected in one class of sepa- 
rator by making an abrupt change in the direction of the steam and 
water. In another class there is, in addition, a centrifugal action, by 
means of which the water is thrown to the bottom of the separator 
and drained off, the steam rising to the controlling valve. 

An excellent iseparator can be made as follows: Take a short 
section of pipe of large diameter; cap the bottom end; connect a 
drain valve to the capped end; fit a gage glass on the side of the 
pipe near the bottom; cap the top end, and through this cap secure 
the outlet end of the steam pipe ; let it extend down vertically from 
the cap on the inside of the pipe a distance of about four times its 
diameter ; from the side, near the top and well above the end of the 
outlet steam pipe, secure the steam inlet pipe. The entering steam 
current is then changed quickly, first through 90°, then through 
180** and the entrained water is thrown to the bottom of the pipe, 
where, if connected to a trap, it is discharged to the feed tanks, or, 

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if not, it is drained to the bilge by opening the drain valve when the 
gage glass shows water in the separator. 

The Stratton centrifugal separator is shown in Fig. 67. The 
wet steam enters at the right of the figure 
and passes around the central pipe in a spiral 
direction, as shown, the heavier particles of [ 

water being thrown, by centrifugal action, ' 

against the sides of the casing. The water 
runs down into the reservoir below, and the 
dry steam, after reaching the bottom of the 
central pipe, passes into it and out of the 
separator by the upper opening at the left, 
and thence to the engines. The reservoir is 
fitted with the usual automatic gage glass 
and a drain pipe at the bottom. 

It was found in practice that, when steam 
of high pressure was used, the rotary motion 
imparted to the water as it separated was 
continued, in some cases, especially where the j^ ^^ 

separator was short, down to the bottom of the 
reservoir. This resulted in a layer of water against the sides of the 
reservoir, and a space filled with steam in the center. The gage 
glass would show full and, on opening the drain, steam would be 
blown out. To remedy this defect, by breaking up the whirling 
motion of the water, wings or plates are put in the reservoir, as 
shown, standing at an acute angle to the course of the current. 
These cause the water to settle solidly towards the bottom, and the 
gage glass will give the correct height at all times. 

If the traps on lines from separator to feed tank get out of 
order, they should be bypassed with valves adjusted so that water 
always shows in the bottom of the separator gage glass. If this is 
not done, much live steam may be wasted by blowing it through the 
traps to the feed tanks. 

All drains from steam lines and separators lead to automatic 
traps; the traps are fitted so that they can be bypassed. Traps are 
fitted to discharge into the feed tanks or condensers in order that 
all fresh water possible may be saved for use in the boilers. The 
bypass is made eitlier by connecting the inlet steam to the discharge 
from the trap by pipe connections outside of the trap, or by connect- 
ing the same internal passages in the trap and fitting a valve by 
which the trap can be G^ut off and bypassed. 

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130 Marine and Naval Boilers 

Steam Traps. — There are three classes of automatic traps : 

1. Intermittent flow or bucket traps. 

2. Differential traps. 

3. Expansion traps. 

Intermittent Traps. — Figs. 68 and 68a show the Lytton backet 
trap, which is of the intermittent-flow type. 

Fio. 68. — Lytton Bucket Trap. 

Fio. 68a. — Details of Main and Auxiliary Valves. 

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Boiler Accessories 131 

It consists of a chamber^ a bucket^ a main and an auxiliary valve. 
Discharge pipes lead to and from the chamber and valve chest 
respectively. Water and steam flow through the inlet opening A 
to the chamber and raise the bucket D until it strikes the top of the 
chamber; when the water rises to the top of Dj it overflows into it; 
the bucket D then fills and drops to the bottom of the chamber; 
this causes an upward movement of the lever K, which raises the 
auxiliary valve M and admits the pressure in the trap to the under 
side of the piston attached to the main valve L. This pressure opens 
the main valve and the water is forced out of the trap through 
bucket D, connection Q to pipe Cj and thence to outlet B. The 
water flows from the trap chamber until level with the top of D, 
when it is at its lowest position ; then that in D is blown out until 
D floats (in the position shown) and closes the valves L and M. 
L and M remain closed until D fills and drops again. All parts of 
this trap, except the float, are outside of the chamber, and are 
accessible. All of the automatic functions of the trap can be per- 
formed by hand from the outside by means of the lever shown in 
the end view. 

The bucket or intermittent-flow trap is the one in most extensive 
use in the V. S. Navy. 

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132 Mabinb and Natal Boilees 

Eiely Steam Trap. — Fig. 69 shows the Kiely and Mueller steam 

Water enters the inlet, flows over the deflecting shield D, and then 
down under and up around the bucket B. When the water reaches 
the top of Bj it flows over its edge into B and causes B to sink. B 

FiQ. 69. — ^Kiely and Mueller Steam Trap. 

is pivoted at as shown, and, when it sinks, it pulls the auxiliary 
valve Fi down and admits water to the upper end of the piston P. 

The pressure on top of P permits the main valve V, to which P 
is secured, to open, and the water in the bucket rushes up through 
the casing C and out through the outlet to the drain pipe. When all 
the water is blown out, the water outside the bucket lifts the bucket 
and closes both valves. 

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Sometimes a rod is fitted through the top of the trap so that it 
may be screwed down into the bncket to dnmp the bncket by hand. 

Expansion Traps. — Expansion traps are nsed very little in the 
United States Navy. The principle of the expansion trap is that 
of the control of the discharge of water from the trap by means of 
the control of a valve which is opened and closed by the expansion 
and contraction of metallic parts caused by their change in tem- 
perature due to alternate contact with steam and water. 

Beduoing Valves. — ^The steam pressures carried in the boilers 
and main and auxiliary steam pipes are higher than are necessary 
for many auxiliary engines found on board naval vessels^ and are 
too high for many of the purposes for which steam is used. These 
pressures are reduced either by throttling the steam by use of the 
throttle or control valve, or by interposing a reducing valve in the 
branch from the main or auxiliary steam lines between the line and 
the machine for which the steam is needed. 

As there are generally many different pressures required for the 
various machines connected to the auxiliary steam line, the throt- 
tling method will not answer; so the method of using reducing 
valves placed in the branches from the auxiliary line is resorted to. 

By means of the reducing valve the steam pressure on the low- 
pressure side of the valve is automatically kept constant at the 
pressure for which the valve is set, as long as the pressure on the 
high-pressure side of the valve is greater than that on the low- 
pressure side. 

The following three reducing valves are used extensively in the 
U. S. Navy, 

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134 Marine and Naval Boilebs 

The Lytton Seducing Valve. — Fig. 70 shows the Lytton Bedncing 
Valve. The parts of this valve are as follows: 

1. Fixed top of spring 3. 

2. Adjusting nut. 

Fig. 70.— Lytton Reducing Valve. 

3. Adjusting spring. 

4. liock nut for adjusting nut. 

5. Hexagon on adjusting-spring casing. 

6. Base of spring 3. 

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7. Diaphragm. 

8. Valve bonnet. 

9. Guide for pilot-valve piston. 

10. Plugs for cleaning or examining passage 11. 
U. Steam passage for reduced steam to chamber under dia- 
phragm 7. . 

12. Pilot valve. 

13. Steam passage from top of piston 16 to top of pilot valve. 

14. Pilot-valve spring. 
16. Valve casing. 

16. Piston to main valve 18. 

17. Steam passage from inlet steam to under side of pilot valve. 

18. Main valve. 

19. Main-valve spring. 

20. Lower bonnet to valve chamber. 

21 and 22. Studs and washers to lower bonnet. 

The pilot valve 12 is kept open by the adjusting spring 3, pressing 
against the diaphragm 7, which transfers this pressure to the stem 
of the pilot valve 12. Steam enters the valve chamber through the 
inlet, rises through steam passage 17, and passes through the pilot 
valve and through the passage 13 to the top of piston 16. Owing to 
the large area of 16, the main valve 18 is opened against spring 19 
and against the inlet pressure. 

Steam now passes through the main valve to the outlet, the pres- 
sure being reduced by the throttling action of the main valve. 
Steam in the outlet chamber has access through passage 11 to the 
under side of diaphragm 7. 

The valve is set by the action of the adjusting nut 2 on the 
adjusting spring 3. As the pressure in the outlet chamber rises 
above that for which the valve is set, it tends to raise the diaphragm 
and allows the pilot valve 12 to close part way. This reduces the 
pressure on top of 16, enabling the inlet pressure and spring 19 to 
partly close the main valve and reduce the outlet pressure. If 
the outlet pressure is too low, diaphragm 7 is forced lower by 3; 
this causes a higher pressure on top of 16 and a consequent greater 
opening of the main valve. 

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Mabine and Natal Boilbes 

The Poster Pressure Begulator. — The Foster Pressure Regulator, 
described in Barton and Stickney^s Naval Eeciproeating Engines 
and Auxiliary Machinery, is shown in Fig. 71. 

Fig. 71.— Foster Pressure Regulator— Class "W/ 

No. Name of Part, 

1 Body. 

2 Upper yalve-seat. 
8 Lower valve-seat. 

4 Maine vfilve (or clap- 


5 Bottom flange (or 

6 Valve (or clapper) 


7 Valve-stem nut. 

8 Vahre-stem Jamb-not 

9 Valve-stem Jamb-nut 


10 Bottom and top fifLUge 


11 Gasket 

No. Name of Part. 

12 Top. 

18 Top liner. 

14 Valve-stem levers. 

15 Valve-stem pin. 

16 Cotter-pin for 16. 

17 Diaphragm center. 

18 Diaphragm center pin. 

19 Diaphragm (set^-con- 

sisting of one or 

20 Diaphragm Jamb-nut. 

21 Hood. 

22 Spring-bolt bracket. 
28 Sprlog-bolt bracket 


No. Name of Part. 
24 Spring-bolt bracket 
anoT hood-bolt nots. 
26 Hood bolts. 

26 Port screw. 

27 Toggle-lever base. 

28 Toggle lever. 

29 Toggle-lever links. 

30 Pivot washer. 

81 Plain yoke. 

82 Lock yoke. 

88 Lock-yoke wrench. 
84 Springs (two to a set) 
86 Spring bolts. 

86 Spring-bolt nuts. 

87 Diaphragm chamber 


The principle of its action is that of wire-drawing the steam by 
throttling or restricting the opening at the main valve through 
which the steam passes from entrance to delivery. The steam enters 

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valve at A, Fig. 71^ and> flowing in the direction indicated by the 
arrows, passes out at B. In its course it enters chamber D, through 
port E, closing valve 4 against the opposing power of the springs 
34. Any increased pressure on the diaphragms overcomes the re- 
sistance of the springs^ lifting valve 4 toward its seats. Should liie 
delivery or reduced pressure decrease, the springs overcome the 
pressure on the diaphragms and force valve 4 open. An equilibrium 
is thus instantly established. The desired delivery pressure is con- 
trolled by adjusting nuts 36 — ^turning to the right increases, and 
turning to the left decreases, the delivery pressure. 

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138 Marinb and Naval Boilees 

Leslie Beducing Valve. — Fig. 72, taken from Barton and Stick- 
ne/s Naval Reciprocating Engines and Auxiliary Machinery, shows 
a sectional view of the Leslie valve, which consists of a main body 
A, containing the main valve D, main-valve spring E, piston F, dia- 
phragm 0, controlling valve J, with its spring K, the adjusting 
spring L, adjusting cap 0, steam inlet R, steam outlet T, inlet port 
8 to controlling valve, and port U to diaphragm chamber. 

Fio. 72.— The Leslie Reducing Valve. 

The action of the Leslie valve is as follows : Steam enters at R 
under boiler pressure and leaves at T under the reduced pressure. 
The figure shows the main valve closed, as it is when no steam is on 
fi. Main valve D is held against its seat by the spring E. Attached 
to the upper end of its stem is the piston F, which works in a cylin- 
der, the top end of which is always in communication with R when 
the controlling valve J opens. This valve is held against its seat by 

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the small spring K, and its stem is independent of the small dia> 
phragm G. The imder side of is always in communication with 
outlet T, and its upper side is subject to the tension of the adjusting 
spring L acting on the block or seat N. 

When the valve is to be regulated after being secured in place, 
the cap is unscrewed until there is no tension on spring L. The 
drain cocks on the delivery side and at the bottom of the lower 
bonnet G (not shown) must be opened, and then the bypass valves 
be opened if fitted, or the stop valve on the inlet side be opened very 
slowly until it is opened full. The cap is now screwed down 
slowly, a little at a time, to allow the regulator to become thoroughly 
heated and drained. When the desired pressure on the delivery 
side has been obtained (the drains being closed when all water has 
been blown out and the delivery pressure is steady), the lock nut 
P is set up tight against 0, and the two are locked together. 

When the cap is screwed down, it puts L under tension. The 
latter forces down and partially opens valve J against the spring 
K and the pressure of the inlet steam, which has been admitted to the 
back of J through the port 8. The steam reaches the top of F 
through the port 7 and forces the piston and the main valve D 
down and partially open. Steam is now wire-drawn from R into T 
and, at the reduced pressure, acts on the bottom of diaphragm 0, 
through the port V, against the tension of the spring L, and acts 
also on the under side of the piston F, through a number of holes in 
the bottom of the cylinder. So long as the pressure in T, and 
therefore that under the diaphragm, balances the tension of the 
spring L, there will be no change in the position of J as fixed by the 
setting of spring L, and hence no change in F and D, But if 
the delivery pressure falls, spring L acts downwards and opens J 
wider, which results in a greater pressure on top of F and a corre- 
spondingly greater opening of D, and therefore in a greater pres- 
sure in T until equilibrium is again restored between the two sides 
of the diaphragm. The action is similar, only in a reversed man- 
ner, when the pressure in T rises. 

These valves are of the same construction for all sizes from ^'' 
to 20", except that all valves larger than 4" must be fitted with 
bypass valves 80 that the pressure on the delivery side can be raised 
before the stop valve on the inlet side is fully opened., in order to 
prevent pounding or other injury. The size of the diaphragm does 
not change with each size of the valve, there being only two sizes 

Digitized by 


140 Mabinb and Naval Boxlebs 

used, one for valves from ^'' to 1^'', and the other for valves 2>" and 
larger. This is made possible because the movement of the dia- 
phragm affects only a smaller controlling valve J, and not the main 
valve D directly. 

Escape Pipes. — There is abaft each smoke pipe a copper escape 
pipe open at the npper end to the atmosphere and extending from 
near the top of the smoke pipe to the boiler compartments. 

In the boiler compartments branch pipes connect the safety-valve 
chambers to the lower ends of the escape pipes; in one of the boiler 
compartments the branch pipe also connects with the auxiliary 
exhaust line. By this arrangement the escape pipe will take care of 
the escaping steam when the safety valves pop and the auxiliary 
exhaust can be turned into the atmosphere. A drain is run from the 
safety-valve chamber to the bilge. 


The discussion of subdivision (a) (Firing Accessories for Coal- 
and-Oil-Buming Boilers) is postponed imtil after the discussion of 
subdivisions (b) and (c). 

(b) Firing Accessories for Coal-Burning Boilers. 

Firing Tools. — The fireman's tools are shovels, short and long 
hoes, prickers, short and long slice bars, and devil's claws. The first 
two need no explanation^ except that the hoes are moderately heavy 
for cleaning fires and lighter for hauling ashes. 

Prickers are round bars with one end flattened and turned up at 
right angles^ the bent-up end often having a stop welded on to pre- 
vent the flat end from entering the fire too far. The length of the 
flat end^ or the position of the stop on it, will depend on the thick- 
ness of fire best suited to the coal used. 

Slice bars are round bars with one end fiattened, and a more or 
less rounded point, so that they can be slipped easily between the 
grate and the fire. 

The devil's claw is something like an ordinary rake with five or 
six heavy prongs. It is not much used, most firemen preferring 
the hoe. 

All of these tools have an elliptical ring turned at the handle 
end, as straight ends are much harder to handle. 

To lighten the work while using Idng hoes in cleaning fires or 
in haiding ashes, a removable cross-bar, called a lazy bar, is placed 
in supports fitted to the furnace door frame and to the ash pit 

Digitized by 



Coal biickets are rounds cylindrical iron buckets with heavy rein- 
forced bottoms. They have two hand grips riveted to opposite sides 
about 8" from the tops. They hold about 100 pounds of the average 
coal. Hooks are also supplied to catch the grips acd hook into an 
eye on the trolley on the bunker trolley rails. 

Time-Firing Device. — The time-firing device is a contrivance for 
making at definite intervals of time a signal by which the fireman 
coals the furnace or works the fire. It insures uniform and regular 
firing of all boilers. The time interval of the signal is varied to 
suit different rates of combustion at different speeds. The signal 
is an electrically operated bell and light on the bulkhead in easy view. 

(c) Firing Accessories for Liquid-Fuel-Buming Boilers. 

The requisite installation for burning fuel oil includes : 

1. Fuel'OU Piping. — Steel piping connecting parts of the fuej- 
oil-buming system. 

2. Fuel'OU Storage Tanks. — ^These are specially constructed 
compartments in which the fuel oil is stored. They correspond to 
coal bunkers in a coal-burning ship. 

3. Booster Pumps. — Pumps used to take oil from or discharge it 
into the storage tanks, to take it from or discharge it to a vessel 
alongside, and to pump it into the fuel-oil service pump suction. 

4. OH Service Pumps. — Pumps used primarily to discharge the 
oil through the oil heaters to the burners. They are heavier pumps 
than the booster pumps, and have suctions to the fuel-oil tanks and 
to the booster pump discharge pipes. 

6. Hand Pumps. — Small high-pressure pumps used to pump oil 
into the burners by hand when no steam is available. 

6. Pressure Oil Heaters. — Appliances in which oil is heated by 
means of steam to reduce its viscosity, so that its atomization in 
the burners will be effected more readily. 

7. Strainers. — Basket strainers fitted in the suction and discharge 
pipes of the booster and oil service pumps to remove dirt from the oil. 

8. Oil Burners. — Devices to which oil is supplied under pressure, 
and in which it is atomized or broken up into minute particles so 
that it will bum more readily in the furnace. 

9. Air Registers. — Devices in the casing of the boiler for ad- 
mitting and regulating the supply of air for combustion of the oil 
in the furnace. The air registers are made in various shapes, cylin- 
drical, conical and discal. The conical registers are also known as 


Digitized by 


142 Marine and Naval Boilers 

air cones, and the discal ones as impeller plates. The burners are 
set in the registers and project toward the furnace space. Properly 
speakings an air register should have a regulating shutter. Air 
registers are also called tuyeres, 

10. Meters, — Oil meters on the oil service-pump su/ition or dis- 
charge, to measure oil consumed by the boiler. 

11. Heating Coils, — Steam coils around the suction pipes in the 
fuel-oil storage tank to reduce the viscosity of the oil so that it may 
be drawn readily into the oil pump suction pipe. 

12. Automatic Stop Valves. — Automatic valves placed in the oil 
service pump discharge pipe to cut off the supply of oil in case of 
rupture of the oil line to the burners. 

13. Necessary fittings, such as valves, drains, gages, etc., to all 
the appliances previously given. 

Fuel-Oil Piping. — Oil piping is made of seamless drawn steel with 
steel flanges. Either the flanges are screwed on with pipe threads 
and the pipe is expanded in the flange, or the pipe is expanded into 
^oves in the flange. All joints and fittings are made tight by 
metal-to-metal joints; i. e., there are no gaskets used.* Suction 
pipes must be tight under a pressure of 50 pounds per square inch ; 
and discharge pipes, under a pressure of 600 pounds per square inch. 
On vessels using fuel-oil as auxiliary with coal, suction pipes lead 
from the double-bottom storage tanks to engine room manifolds. 
Heavy simplex pumps in engine rooms discharge the oil through 
strainers into a main, branching in the fire rooms to run outboard 
of the boilers and to thu^s supply the burners through pressure oil 
heaters. A storage tank filling pipe runs imder the main deck 
from side to side, having hose connections at the sides. A vertical 
pipe connects this athwaitships pipe with a cross-connecting pipe 
between the suction manifolds. Heavy air chambers are located on 
the suction and discharge sides of the simplex pumps. 

Fuel-Oil Storage Tanks. — ^The liquid fuel is placed in oil storage 
tanks ; each tank has suction pipes leading to the storage-tank mani- 
folds in the fire-rooms. The oil storage tanks, in battleships, are 
specially constructed structural compartments. In destroyers, they 
are specially constructed tank compartments, forward of the fire- 
rooms and abaft the engine-room. 

The double bottom storage tanks on battleships using coal and oil 
have each the following connections, besides suction piping : 

1. Vent pipe (sheet iron) leading from tank top to main deck 
(well screened) . 

2. Sounding tube (wrought iron) with valve, cap, and locking 

* In practice, gaskets sometime.? have to be used; in such cases they 
are made by using between the flanges a coat of shellac or oil paper. 
The oil paper can be made by soaking a piece of an old chart In oil. 

Digitized by 


Boiler Acgbssories 143 

3. Steam connections for fire extinguishing and for steaming out 
the tank. 

4. Salt water connection for expelling gas and for cleaning. 

5. Warning device and automatic float cut-off valve, to operate 
when the tank is 95 per cent full. 

The storage tanks of battleships using fuel-oil only are double- 
bottom compartments forward of the fire rooms, and abaft and under 
the engine rooms, and other special compartments not directly 
adjacent to heated compartments. They are provided with two suc- 
tion pipes called high and low, the latter being used for draining off 
water or when oil is low, with viscosity reducing steam coils, with 
vents, with steam fire connections, and with measuring device. The 
storage tanks of destroyers make use of the vessel's skin as parts of 
the tanks, and often extend from side to side. Each tank is fitted 
with these connections : 

1. One or more air escape and overflow pipes (iron), fitted with 
valves and mushroom heads. 

2. Sounding tube (wrought iron), with guard at lower end and 
plug and lock at upper end. 

3. Steam connections to near bottom for reducing oil viscosity and 
at top for fire extinguishing. 

4. Filling connection. 

5. Manhole and manhole plate with lock. 

6. Drain pipe from tank bottom. 

Storage tanks require special joints. Flange joints outside of 
tanks are made with two layers of No. 10 canvas soaked in raw lin- 
seed oil and painted with thick red lead. Their through bolts are 
packed under heads and nuts with lamp-wick soaked in red lead. 
These joints are sometimes made with pasteboard saturated with a 
mixture of 20 parts wax and 10 parts varnish. The rivets are 
closely spaced and seams are calked on both sides. 

The amount of oil in a storage tank is registered by an instrument 
called a pneumercator (see page 232). 

Booster Pumps. — ^The booster pumps are similar in design to the 
simplex piston tjrpe of pump described under feed pumps, though not 
constructed to give such heavy pressures, hence they are sometimes 
called light-service pumps. They have metallic valves, and have 
large vacuum chambers on their suction sides and large air chambers 
on their discharge sides. They have suctions to storage-tank mani- 
folds and to the filling pipe connected to the ship's side. They have 
discharges to storage-tank manifolds, fuel-oil main, service pump 
suction, and main deck for supplying galley. They have also a 
discharge at ship's side for oil transference and an arrangement, by 
portable connection, for discharging overboard oil or water from 
the tanks. 

There are strainers of the basket type both on the suction and on 
the discharge sides of these pumps. 

Digitized by 


144 Mabinb and Naval Boilers 

Duplex oil service pumps of the piston or plunger type are in- 
stalled in each fire-room; they have suction pipes through twin- 
basket strainers leading to oil storage tank, fuel-oil main, booster 
pump discharge, and to burner supply line for draining it, and have 
discharges through duplex basket strainers to oil pressure heaters, 
and from the heaters to the burner supply pipes for all boilers. These 
are heavy-pressure pumps. These pumps have large vacuum cham- 
bers on their suction sides, and large air chambers on their discharge 
sides. In the discharge pipe from the pressure heaters to the burners 
of each boiler, there is a master valve fitted ; this valve is so arranged 
that it can be operated from the deck above. It controls the oil 
supply to all burners of one boiler. The following fittings, 
besides those already mentioned, are attached to each of these pumps : 
pump governor, adjustable spring relief valve, and pressure gages 
(on discharge pipe, each side of strainer) . 

Hand Pumps. — One hand oil service pump is installed in each 
fire-room for use when getting up steam in one of the boilers of that 
compartment when there is no steam on the vessel for running the 
duplex oil service pumps. These pumps supply oil at a pressure of 
200 pounds per square inch to two burners. Each has a suction to 
the fuel-oil main in its compartment and discharges to the burner 
supply pipe. It also has a suction to the storage tank drains, and a 
discharge overboard, by means of which the water may be pumped 
overboard from the bottom of the storage tanks. 

The pressure oil heaters are located in each fire-room, and have 
sufficient heating surface to heat all the oil used in the boilers in 
that fire-room when steaming at the maximum rate of combustion. 
The oil may be heated to any desired degree, but should never be 
heated above flash point. They are similar in design to the pressure 
feed-water heaters. (These feed-water heaters, have been described 
in an earlier part of this chapter.) 

The Schutte-Koerting Film Heater installed on the Utah is 
shown in Fig. 75. 

The pressure heaters are so arranged that they can be bypassed 
if desirable. The heaters take steam direct from the auxib'ary steam 
line and are drained to the feed and filter tanks through traps. 

Digitized by 


BoiLBR Accessories 145 

6000 lbs. 
1 per hour* 
r. to 250* 
»am at 200 

■ arface, 

I at D. 
bers at C. 

Fio. 76.— Schutte-Koerting Film Heater. 

Digitized by 



Marine and Naval Boilers 

These traps have gage glasses and fittings^ by which the condensed 
water may be drawn off and tested for oil. The gage glass should 
be carefully watched, as oil leaks may be detected at this point, thus 
preventing fuel oil from getting into the boiler feed. 

Oil heaters of the straight-flow and coil types are also used. 

Oil Strainers. — Twin-basket strainers are fitted, and are so ar- 
ranged that one strainer can be bypassed and the basket be removed 
and cleaned while the other is in use. The twin-basket strainer 
shown in Fig. 76 is made by the Elliott Company. The ends of the 
compartments A, A can be easily removed, and basket be removed 



^do o o o 


oo o 

oo o 

oo o 

o o. oooooo 



Fio. 76.— EUiott Strainer. 

and cleaned. The valves B, B, operated by hand wheels C, C, direct 
the oil through either one or the other of the baskets. 

Oil Burners. — There are three classes of burners for liquid fuel. 
The classification is made with regard to the method used in atom- 
izing the oil by the burner. 

The three methods of atomizing the fuel are : ( 1 ) Steam atomizor 
txon, (2) air atomization, (3) mechanical atomization. 

The steam atomizing burners use from 3ji to 6^ of the steam 
generated by the boiler, and are therefore impracticable for marine 
use on account of the fresh water required to make up for that ex- 
pended in the burner. 

Air atomization requires large, heavy air compressors to give air 
under the requisite pressure for atomization. While this system 

Digitized by 


BoiL£B Accessories 147 

entails no loss of fresh water, it requires much steam to give the 
necessary power for compressing the air. The compressors take up 
much room and require special attendance. 

Mechanical atomizaiion is accomplished by having the oil in the 
burner under a comparatively high pressure. Both the shape of 
the burner nozzle and the internal fittings of the burner play an 
important part in the character of the atomization. 

The oil service pumps give the required pressure (about 200 
pounds), and they are attended by the regular fire-room force. 

Mechanical atomization is the only practicable method for use 
with marine boilers at present, and is the only method in use, at sea, 
in the navy. For use in port, to avoid the large steam consumption 
of the blowers, the Ingram burner (a steam or air atomizer) has 
been in extensive use. Air compressors are fitted on some destroyers 
to provide for air atomization in port 

There are oil strainers fitted to each individual burner. They 
are so designed that they may be easily and quickly opened, 
cleaned, or removed without interference with other bujrners. 

Burners are fitted in air registers. 

In the burners now in use, the atomization is caused by the 
action of centrifugal force when the oil is given a rapidly revolving 
motion in the burner. The spray of oil issues from tho burner tip 
in a cone without a whirling motion. 

The burners are usually arranged to diverge in the direction of 
discharge, in order to prevent the flames from impinging on each 
other, and are always arranged to discharge so that the flame will 
not impinge on the lower row of tubes or on any part of the heating 
surface of the boiler. They are so fitted that the tips of the burners 
are in the furnaces, and the service pipes and regulating valves are 
in the fire-rooms. 

As previously stated, all burners for mechanical atomization of 
oil incorporate the principle of forcing oil under high pressure 
through passages in the burner so arranged as to give tlie oil a high 
velocity of rotation and thus break it up under the action of centrif- 
ugal force. The rotary motion is given either by a helical con- 
struction of the atomizing head or by a tangential entry of the oil 
from a peripheral to a central passage in the head. Tho capacity of 
the burner, i. e., the quantity of oil burned per hour, depends upon 

Digitized by 


148 Mabinb and Naval Boilbbs 

the pressure and temperature of the oil and the diameter of the 
opening in the burner tip, increasing up to certain practical limits 
with the increase of these two factors. In some types of burners, the 
capacity of the burner may be varied by changing the openings of 
the passages in the atomizer head by means of a regulating spindle 
projecting into the passages. This construction makes the burner 
more complex and introduces the probability of being unable to 
adjust the openings of all burners exactly the same. For use in 
port, extra burners of reduced capacity are now supplied. 

The principle of all mechanical atomizing burners will be under- 
stood from a study of the Bureau of Steam Engineering Standard 
Burner, Plate XVI. 

Oil imder pressure enters the burner through the oil pipe and 
passes through the burner pipe to the burner plug. Here it passes 
through ports P^ and Pj ^ the outside of the end of the plug, 
which is reduced in diameter to form a space S, from which the oil 
enters four tangential slots T8 and is directed inward from S to 
the atomizing chamber AT. From the chamber AT the oil is 
sprayed through the central outlet passage in a finely atomized 
cone. The ball-and-socket joint at the elbow permits the removal 
of the burner for examination or repair. The burner tips are 
removable. The angle of the oil cone is 90®. A slight variation 
from this angle does not affect the efficiency of the cone. 

The Ingram burner, which is used in port by the destroyers and 
which employs either steam or air to atomize the oil, is shown in 
Fig. 77. Steam or compressed air enters the burner at the pipe 
marked " steam,'* and goes out through pipe a to the burner tip ; 
oil enters from below and reaches the tip tiirough the pipe 6. At 
the tip the oil works down through the five channels marked c (end 
view) and is blown out through the narrow horizontal slot by the 
compressed air. The oil leaves the burner in a narrow sheet which 
widens as it advances. 

Oil Fuel for Battleships. — In battleship boilers fitted to bum coal 
and liquid fuel, both singly and together, the arrangement of the 
burners and furnace doors is such that no change in the furnace 
fittings is necessary to shift from coal to liquid fuel, or vice versa. 
The burners are fitted in pairs through the furnace fronts between 
the furnace doors, and are so arranged that either burner and its 
strainer of the pair can be in operation while the other one of the 
pair is being cleaned or overhauled. When boilers for battleships 

Digitized by 


Digitized by 


Digitized by 


Boiler Agobssobibs 149 

are designed for use with liquid fuel only^ the arrangement of their 
burners, air registers and air casings is similar to that in the present 
liquid-fuel-buming destroyers. 

Air Begisters. — The registers in use in the IT. S. Navy are of 
two general types^ the conical and the discaL 

The conical type is made in the shape of the f rustrum of a cone, 
with slots down the side of the cone of such cross-section as to give 
the air a rotary motion and with adjustable shutters to regulate the 
quantity and velocity of the air entering the slots. Begisters of 
this type are commonly called air cones, and are now standard in 

Fio. 77. — Ingram Burner. 

the U. S. Navy. The cones are usually secured between the outer 
and inner plates of the boiler front casing. In some types of boilers 
where the air space between the outer and inner plates of the front 
casing is small, the cones are secured through both casings at their 
large ends and project from the boiler front into the fire-room. 

The discal type is made from flat plates with radial slots of such 
shape as to give the air a rotary motion. It usually has no regulat- 
ing shutter, the openings being considered with tiie design of the 
blowers and the air being regulated by doors in the outer casing. 
Begisters of this type arc installed on some of the IT. S. battleships. 
They are called impeller plates. 

Digitized by 



Marinb and Naval Boilers 

















, ^/, 



,' / ' 

















' 1 



1 ' 

i', \ \ ^ 


: \ \ \ %>•: 


Digitized by 


Boiler Agcessoribs 151 

The Peahody Impeller Plate shown in Fig. 78 is fitted by the 
Babcock and Wilcox Company to their boilers burning oil alone 
or oil in conjunction with coal. The vanes of the impeller are set 
at an angle of 45** to the plane of the impeller plate. Air is admitted 
to the space between boiler front plates by non-return swing doors, 
as shown. Air is supplied by blowers under the closed fire-room 

Bureau Engineering Natural-Forced Braft Register (Plate 
XVII). — The details of the earlier registers varied considerably. 
The principle of all may be imderstood from the sketch of the 
Bureau of Engineering Natural-Forced Draft Register, Plate XVII, 
which incorporates the ideas of most of them. 

The register 1 is bolted through the angle ring 4 and straight 
ring 3 to the boiler front. Details of air register are shown in 
small sketch. The position of the atomizer 36 is controlled by 
means of a rack, not shown, on pipe 37 and pinion 28 operated by 
handle 32. 

Digitized by 


162 Mabine and Natal Boilbrs 

(a) Firing Accessories for Coal-and-Oil-Burning Boilers. 
Tools and Appliances for Handling Ashes and Soot. 

Ash buckets are cylindrical backets with eztra heavy bottoms. 
They have a bail pivoted in pads on the sides of the backet near the 
top. The bail has an eye or bend at its center part^ into which the 
hook on the ash hoist-engine wire engages when hoisting ashes. 
These buckets hold approximately 100 pounds of ashes when filled. 

Ash hoist engines are simple steam engines operated by a differen- 
tial valve. There are generally two simple steam cylinders working 
on the ends of the same shaft. The shaft operates a drum around 
which the hoist wire is wound. The valve is operated by a hand 
wheel, which works through a gear and opens the valve as the wheel 
is turned. A chasing gear on the shaft operates to close the valve 
as it is turned. By moving the hand wheel, the valve is opened and 
steam is turned into the engine cylinder; and as the engine moves, 
the valve is closed by means of the chasing gear. As long as the 
hand wheel is moved, the engine continues to operate; as soon as the 
motion of the hand wheel is stopped, the engine stops. There are 
lags on the hand-wheel shaft which are so located that the engine 
cannot be operated to hoist the bucket too high, also to prevent it 
being dropped to the floor plates with too much force. The wire 
from the drum leads over sheaves; it hoists or lowers the bucket 
between guides placed in a fire-room ventilator or vertical air duct. 

Ash ejectors are now fitted to all new coal-burning battleships 
and armored cruisers, and have been installed on most of the old 

There are two classes: (1) Those that discharge the ashes abov$ 
the water-line and (2) those that discharge through the sides or 
bottom of the ships. 

There are several makes of each class. The ones, of the first class, 
used in the navy are the Davidson and See, which consist of hop- 
pers into which the ashes are thrown, and from which they are re- 
moved by the action of a jet of water under pressure. The ashes are 
forced out through a cast-iron pipe leading to the side of the ship 
above the water-line. The pipe is made extra heavy at all bends, to 
allow for the scouring action of the ashes; in some cases the pipe 
has removable pieces placed at the outer curve of all bends. With 
ash ejectors of this type the water is forced into the pipe through a 
uozzle, thus forming the jet. The ashes are washed into the jet by 

Digitized by 


J \ 

Digitized by 


Digitized by 

















Digitized by 


154 Marinb and Naval Boilbbs 

small streams of water forced into the hopper around its sides^ and 
also by the suction caused by the jet. Great care must always be 
taken to see that the nozzles are set with the proper opening to 
form the jet, and also that the jet is formed in the center of the 
pipe; otherwise the jet will cut the pipe, due to the scouring of the 

There are two types of the under- water ash ejector — the pneu- 
matic and the hydraulic. These types are coming into use on 
the newer ships. There was objection to this type for many years, 
as it was claimed that' (1) the scouring action of the ashes wore 
away the outer plating, (2) the ashes entered the main injec- 
tion pipes and clogged the main condensers, and (3) they entered the 
strut and stern tube bearings, causing them to cut and wear away 
rapidly. Objection (1) has little weight, objections (2) and (3) 
were overcome by placing the discharge orifice below the bilge keels, 
and this class of ejector is coming into general use. 

A type of under-water ash expeller is the Newport News Ship- 
building Company^s Ash Discharger, shown in Fig. 79. 

Ash Wets. — In each fire-room a small connection is made to one 
of the sea suction-valve casings below the valve. This connection 
has in it a valve and a hose coupling. A small hose is secured to this 
for wetting down the ashes and clinkers when cleaning fires or for 
running water into the ash pans if necessary. 

Tube blowers are for the purpose of removing soot and cinders 
from the fire side of the tubes; and there are many types in use. 
For fire-tube boilers a steam lance, connected to the auxiliary steam 
line by means of a steam hose, is generally used. The lance is placed 
in the outer end of the tube, and a jet of steam is blown through the 
tube, sweeping the soot and cinders into the combustion chamber. 

For water-tube boilers the lance is connected to the auxiliary 
steam line in the same way as above. It is carried on a jointed 
handle, and is shoved in between rows of tubes ; the steam jet blows 
the soot from the tubes. In cleaning tubes by blowing the soot from 
them by steam or air the path of the gases of combustion should be 
followed, beginning with that part of the path where the gases 
enter between the tubes; t. e., in a Babcock and Wilcox boiler the 
first pass would be blown, then the second, and finally the third pass. 
After the tubes are blown, the soot and cinders should be raked from 
the upper sides of all nearby horizontal baffle plates. 

Digitized by 


Boiler Accessories 155 

In ships that have a pneumatic line running through the fire- 
rooms, a connection is made in each fire-room for blowing the tubes 
with compressed air. 

In some types of water-tube boilers of recent manufacture, per- 
forated pipes are fixed in position between the tubes, in locations 
where the soot and cinders are most likely to collect (see Plate V). 
Each of these pipes is connected to a branch from the auxiliary 
steam line, and steam is controlled by its own valve. This branch 
has a valve at the auxiliary line ; below this valve a line connects the 
branch with the pneumatic line. Either steam or air can be used 
for blowing tlie tubes. In any case where the soot and cinders have 
become wet and packed too hard for removal by blowing, or where 
from leaky tubes salt scale has formed between them, the obstruc- 
tion must be removed by scaling bars. 

Tube brushes are used for removing the soot and scale from the 
fire sides of fire tube boilers. The one 
in general use in the navy is a metal 
cylindrical brush with the metal 
bristles arranged around its stem in 
the form of a helix (see Fig. 81). 
The brush is screwed into a handle 

and is worked back and forth through Piq. 81.— Wire Tube Brush, 
the tube xmtil it is clean. The same 

style of brush is used for removing a light mud scale from the watei 
sides of water tubes. 

Scale-Bemoving Tools. 

Tube cleaners, for removing the hard scale and rust from the 
water sides of water tubes, can be subdivided into three general 
classes: (1) Those that remove the scale by hammering, (2) those 
that grind it away and (3) those that scrape it from the metallic 

The first two classes are generally turbine-driven, either air or 
water, under pressure, being used as the motive power. Most tur- 
bine cleaners have cutters so arranged that one set does the ham- 
mering while another set does the cutting. 

Digitized by 



Marine and Naval Boilehs 

Fig. 82 shows the Weinland water-driven turbine cleaner, with 
different cutters shown at a, b, c. d is the turbine wheel. 

The hose D connects the chamber of the turbine with the pump 
discharge. The water passes through the buckets of the water wheel 
B and gives a turning motion to spider 0; the arms K, carrying the 
cutters L, are thrown out against the sides of the tube by cen- 
trifugal action, and the cutters grind away the scale. The water. 



A — Case. 

B — Water wheel. 

C— Spider. 

D — Hose coupling. 

E — Ball-races. 

F— Center bolt. 

O — Cone. 

H— Balls. 

/ — Screw for oil chamber. 

J — Oil chamber. 

K — Arms. 

L — Cutter wheels. 

M — Arm Screws. 

N — Cutter pins. 

— Nut for center bolt. 

Fig. 82. — Weinland Turbine Tube Cleaner. 

after it escapes through the water wheel, washes away the scale as 
it is ground oflE. These cleaners are made in sizes to fit the tubes, 
as required. 

Turbine cleaners must be used with care; if they are held too 
long in one place, erosion of the tubes will result. 

Digitized by 


Boiler Accessories 157 

Dampers are heavy doors placed in the uptakes of boilers for regu- 
lating the amount of air flowing through the furnace, and thereby 
regulating the rate of combustion. They also prevent air from 
being drawn into the smoke-pipe through idle boilers connected 
to the same pipe. These dampers are so arranged that the amount 
of opening may be varied at will from closed tight to full open. 
They must be made heavy to prevent warping under heat; must be 
maintained in such condition that they can be closed tight; and 
must be capable of easy control. 


There are two methods of increasing the draft of air through 
the fuel of a furnace: (1) By using air or steam jets in the base 
of the smoke-pipe ; these create a partial vacuum and cause a greater 
flow of air through the furnace and a higher rate of combustion ; (2) 
by using mechanical blowers. The first method is impracticable 
for use with marine boilers, as too much fresh water ^^ould be used 
with steam jets, and the machinery necessary to furnish compressed 
air for the air jets would be too heavy. The second method, that 
of forcing the air through the furnaces with blowers, is the one 
used in naval vessels. 

Forced-Di'aft-Blowers. — There are two systems in use for forcing 
the draft with blowers: (a) The closed ash-pit system, in which 
blowers draw air from an air duct or from the top of the fire-room 
and discharge it into the ash pans and air casings of the boilers 
through air ducts; and (b) the closed fire-room system, in which 
the blowers draw air from an air trunk, open to the atmosphere at 
its upper end, and to the blower suction at its lower end, and dis- 
charge the air into closed fire-rooms, from which it can escape only 
through the furnaces. The closed fire-room system is the one in 
general use. 

The blowers in use, both in the closed ash-pit system and in the 
closed fire-room system, are high-speed centrifugal fans. Air is 
drawn in at the center of the fan and discharged at the periphery, 
either into the closed fire-room or into ducts leading to the ash pita 
and air casings. 

The complete blower consists of: (1) The motive power, a 
steam engine, a small steam turbine or an electric motor; (2) the 
fan; and (3) the fan casing. 

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158 Marine and Naval Boilers 

Fig. 84 shows a sirocco fan connected to a Terry steam turbine. 
The casing of the fan (not shown) has a suction, opening at its 
center, leading to the air trunk, and discharges at the periphery of 
the fan into the trunk leading to the closed ash pit or into the closed 
fire-room. The latest battleships have motor-driven fans with the 

Fig. 84. — Terry Steam Turbine and Sirocco Fan. 

motor control, which will give at least ten different speeds, operated 
from the fire-room fioor plates. 

The blowers are placed in the upper part of the fire-rooms. Pro- 
vision is made for circulating the air in the upper part of the fire- 
rooms to prevent the accumulation of explosive liquid fuel gases. 
In some cases, where the blower fans are driven by steam engines 
or turbines, an automatic control of the blower speed is installed, by 

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BOILEB AccBssoRnss 


means of which, when the steam pressure falls, the control valve to 
the engine is opened and the draft pressure is increased. If the 
steam pressure rises above that for which the control is set, the 
engine valve is partially closed and the draft pressure decreased. 


A description of the testing accessories will be found in the 


Whistles and Sirens. 
From the auxiliary steam line, branches are taken and extended 
forward of the forward smoke-pipe to a height well above the bridge. 
A whistle is attached to one of these pipes, and a siren to the other. 
There are valves to the branches where they are taken from the 
auxiliary steam line ; valves are also placed in the supply lines just 
below the whistle and siren, at positions easily accessible from the 
bridge. The valves near the bridge are for use in shutting steam off 
the whistle and siren in case either should be jammed open while in 
operation ; in case these valves are not installed, the order from the 
bridge must be telephoned to the engine-room and transmitted to 
the foi-ward fire-room, and a man be sent up to close the branch 
stop valve — ^an operation taking appreciable time from the instant 
the defect is noted until the valve is closed. All whistle and siren 
steam pipes should have a separator installed just below the whistle 
or siren. 

One form of this separator, called a water arrester, is shown in 
Fig. 85. The arrows on the sketch show the path of the steam. 

Water is collected in the bottom of the 
arrester and blown out through an auto- 
matic trap. The drain answers two pur- 
poses: (1) To ensure the proper sound 
the instant the steam reaches the whistle 
or siren, and (2) to prevent water being 
blown out on the bridge or deck when the 
valve is first opened. 

Drains from the branches from the 
auxiliary line are also fitted just above the 
branch stop valve and connected to a trap. 
These drains are to drain the pipe when 
steam is shut off at the branch stop valve, 
to prevent the pipe from bursting in freezing weather. 

^ma/rf fc kVA/f^/s or J/>«^- 

J>rS*n ' \ 

Pig. 86. — ^Water Arrester. 

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160 Marine and Nayal Boilers 

The tone of a whistle depends chiefly upon the pressure of the 
steam or air blowing through it and the length of the column of 
air or steam inside of the bell. In most whistles the length of the 
bell can be varied, as will be shown later. When a whistle is in- 
stalled, it should have a reducing valve installed in the brancli 
steam line leading to it. The bell on the whistle and the steam 
pressure to it should be adjusted by trial, so that the whistle gives 
the tone and degree of loudness desired. 

For navigation purposes the sound signalling apparatus on all 
steam vessels is the whistle. On naval vessels a siren and a whistle 
are both installed — ^the siren on the forward side of the forward 
smoke-pipe for signalling ahead, and the signal whistle abaft the 
after smoke-pipe for signalling to vessels astern. The siren is also 
used for signalling in the interior conunxmication system of the 
ship itself. 

The three most familiar forms of steam whistles are the bell 
whistle, chime whistle and shrieking whistle. They are all con- 
structed on the same principle; the sound is produced by steam 
issuing from a narrow circular orifice and striking the thin edge of 
a cylindrical bell, which is secured at a certain distance above the 

Chime whistles are no longer installed on naval vessels, tljough 
there are many now in use. Fig. 86 (a) shows a three-chime whistle 
made by the American Steam Oage and Valve Manufacturing 
Company. The bell is the long cylinder at the top, and is adjust- 
able on a vertical central rod by means of a thread, the nut on top 
securing the bell in place. The cup-sha^d part, immediately below 
the bell, contains a narrow annular orifice in its fiat surface, through 
which steam passes from the operating valve below. There are three 
compartments in the bell, as shown, each of a different length and 
producing a different note. These notes harmonize under the proper 
conditions. Steam is admitted to the cup-shaped bottom of the 
whistle by a valve, which is opened against the steam pressure and a 
spring by the bell crank lever, operated from the bridge by means of 
the whistle pull. This valve is bypassed on whistles for some of the 
battleships and armored cruisers, and an electrically controlled valve 
is installed in the bypass. The current for operating the electrical 
control is sent through a clock-work mechanism, which can be set 
to blow the whistle at certain definite intervals of time, and by 
means of which the length of the blast can be regulated. 

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Boiler Accbssobies 161 

The bell whistle is similar to the chime whistle^ except in the 
make of the bell. It is not ent away at the bottom as in the chime 
whistle, the interior being a plain cylinder not subdivided. Only 
one note is produced by a bell whistle with a given adjustment of 
the bell and the steam pressure; so a reducing valve, set at the 
pressure to give the proper note, is a necessity. 

(a) Chime WhisUe. (b) Shrieking WhisUe. 

FiQ. 86.— Forms of Whistles. 

The shrieking whistle, shown in Fig. 86 (b), made by the Lun- 
kenheimer Company, is similar to the bell whistle, except that there 
is a movable piston inside of the bell, by means of which the length 
of the column of air can be changed at will, and a succession of ris- 
ing or falling notes be produced. The adjusting thread and nut 
are, in this case, below the bell. 


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162 Mabinb and Nayal Boilebs 

PiQ. 87. — steam Siren. 

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The siren is a more powerful instniment than the whistle. It 
is made with a trumpet mouth or megaphone, which can be turned 
to project the sound in practically any direction, thus making it 
more efficient as a fog signal than the whistle. Fig. 87 shows the 
form of siren used in the naval service. Steam is admitted at 7 
by means of a valve (not shown) similar in construction and con- 
trol to that of the whistle. Steam fills the annular chamber 0, 
which is pierced at its upper inner part by a number of vertical 
bevelled slits. A cup-shaped wheel W, pierced by similar slits, but 
bevelled in the opposite direction (shovm in the small sectional 
view), is fitted to revolve freely on the central spindle 8. As the 
steam from rushes through the outer slits and against the sides 
of the slits in W, it causes the latter to revolve at a high rate of 
speed. The alternate closing and opening of the slits sets up violent 
vibrations in the column of air and escaping steam in the mega- 
phone or trumpet-shaped outlet fitted above T. The pitch of the 
soimd will depend on the speed of the wheel, which, in turn, depends 
upon the opening of the controlling valve for any constant pressure. 
Should the wheel, when it stops revolving, close all of the outer 
slits, the siren can still be started by means of the auxiliary holes 
H, the spacing of which is different from that of the slits. In other 
forms of sirens the slits are spaced unevenly, and no auxiliary holes 
are necessary. The method of balancing and supporting the wheel 
is shown. A and B are adjusting bolts for the spindle, access to 
which is given by the hand holes. The trumpet mouth or mega- 
phone, shown to a reduced scale, is fitted to turn, either directly by 
a handle, or by means of gearing from below. Drains are fitted 
to the spaces both above and below the wheel T7 in cold weather; 
the siren must always be properly drained. 

Calking Tools. 

There is much difference of opinion in regard to the proper shape 
of the calking tool and the proper shape of the plate edges in order 
to obtain the best results in calking seams. 

The illustrations of the tools used, and of the results obtained 
from the way of holding them, shown in Fig. 88, are from Stro- 
meyer's Marine Boiler Management and Construction, 1907 edition. 

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Marine and Naval Boilbrs 

1 shows the shape of the calking tool and the proper way to hold 
that tool when the edge of the plate is square; 2 shows the resnlt of 
calking a seam in this manner^ giving fair results; 3 shows the 
same tool improperly held when the edge of the plate is bevelled; 
4 shows the result of calking a seam in this manner, the result 
being bad; 5 shows the proper way to hold this tool against the 
bevelled edge of the plate, and 6 shows the plates after calking. 

Fio. 88. — Calking. 

Although the tool is held properly the result is not good, and a better 
result would be obtained from the use of the tool shown in 7 ; 7 shows 
proper way to hold a round-nosed calking tool against a square- 
edged plate, and 8 shows the result after calking. In calking with 
this shape of tool, care must be taken that it is not too small, 
as it will then act as a wedge and separate the plates. Care must 
also be used in grinding the flat-nosed tool; if the tool has too 
much bevel, the lower edge will bite into the lower plate. 

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Tube Expanders. 

The boiler tube expander, shown in Fig. 89, is of the Dudgeon im- 
proved type. It consists of the body A, inner cap B, outer cap C, 
case-hardened rollers 2> rolling in slots E in body A, and the case- 
hardened tapered mandrel F. 

The rollers I) extend through the body A and are held in place in 
the slots E by the curvatures of their sides. Rollers can be replaced 
by removing cap B and renewing tlie roller in slot E. The body A 
is placed in the tube, and the cap C is adjusted over the end of the 
tube so that the roller extends completely over the tube in wake of 
the tube sheet. The mandrel F is then placed through the central 
hole in body A and bears on rollers, forcing them out against the 
tube. A bar is then placed through hole Q in the outer end of F, 

Fio. 89.— Boiler Tube Expander. 

and the mandrel is revolved. After the rolls have rolled over the 
surface of the tube, the mandrel is driven in and revolved again. 
When done properly, this expands the tube against the tube sheet 
and makes a steam-tight joint. 

In some tube expanders the rollers are so fitted that they feed the 
mandrel through as it is revolved. 

Oreat care should always be taken, in rolling a tube, to see that the 
expander is properly placed, i. e., that the rolls extend on each side 
of the tube sheet and that the tube is only expanded enough to make 
it tight. A great niany boiler troubles are caused by improperly 
rolled tubes. 

The latest practice is to have the ends of the tubes extend through 
the tube sheets or headers a distance of -^'', and to bell the ends 
by an abrupt taper mandrel to ^' greater outside diameter. This 
prevents the tube from drawing through the tube sheet or header. 
. All tube ends are rounded before the expanding tool is used. 

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Heat, according to the accepted modern theories on the subject^ 
is a form of energy. It is usually given the name thermal energy, 
to distinguish it from other forms of energy. Since there exists 
a definite relation between these forms of eneigy, thermal energy 
may be converted into mechanical energy, or vice versa. The ex- 
periments of Rumford, Davy and Joule give ample proof of these 

Thermal energy is inherent in all solid, liquid and gaseous bodies, 
and is due to the velocities and relative positions of the molecules 
in the bodies. Like mechanical energy, it may exist either in the 
kinetic or in the potential form. It is measured by observing its 
effect upon some body. 

Usually, when heat is added to a body, it results in either the 
expansion of the body, or an increase in its temperature^ or both. 
The rise in temperature is a measure of the increase of its thermal 
kinetic energy due to the increased velocity of its molecules. Thus, 
if the velocity of a molecule is denoted by v and its mass by m, the 
kinetic energy of the molecule is i mv^ and that of the system (total 
number of molecules imder investigation) is S i fnv*=Mc*, where 
M denotes the mass of the system. Considerations derived from 
the kinetic theory of gases show that c^ is a function of the tempera- 
ture of the system. Therefore, the temperature of a body or system 
is a measure of its thermal kinetic energy. 

When a body expands, due to the addition of heat, the molecules 
on the whole are relatively further apart, and this separation of the 
molecules against their mutual attraction involves the expenditure 
of work or of its equivalent in heat. The energy utilized to separate 
the molecules of a body is stored up in the body as potential thermal 
energy. Kinetic and thermal energy may be well illustrated by the 
familiar example of heating water. 

When heat is first added to a quantity of water, the effect is an 
increase in the temperature of the water, because the volume of water 

Digitized by 


Heat, Heat Tbansfeb and Evaporation 167 

changes very slightly^ and practically all of the heat is used to 
cause a rise of temperature, that is, an increase in kinetic thermal 
energy. As soon as the water starts to boil, if more heat is added, 
there will be no further increase in temperature, but the water will 
be converted into steam, having a relatively large volume in compari- 
son with the water from which it was evaporated. In this case, the 
energy of the steam has been transformed into potential thermal 
energy and remains stored up in the steam as such. After all the 
water has been converted into steam, if heat is still applied, there 
will be an increase in both temperature and volume; or, in other 
words, the additional heat is manifest in the steam in the form 
of an increase of both kinetic and potential thermal energy. 

It is evident, therefore, that quantities of heat may be measured 
by their effects on different bodies in various states of aggregation. 
In the United States the standard unit of heat is the British Thermal 
Unit (B. T. U.) . It is the 1/180 part of the heat required to raise the 
temperature of a poimd of pure water from the freezing point to the 
boiling point at standard atmospheric pressure. In the C. 0. S. 
system, the unit of heat is the calorie. It is the heat required to 
raise 1 gram of water from 17** to 18** C. on the Paris hydrogen 

Temperature and Sensible Heat. — Temperature is a measure of 
the intensity of heat, and is expressed in degrees by thermometers 
and pyrometers. These instruments may be standardized by noting 
their readings at certain known temperatures, such as the melting 
point of ice (32** F.) and the boiling point of pure fresh water 
(212* P.) at mean atmospheric pressure. 

Sensible heat is the heat which, when added to or taken away 
from a body, will cause a change of temperature in that body. 

Mechanical Equivalent of Heat. — Since thermal and mechanical 
energy are interconvertible, a definite ratio must exist between their 
units of measurement. This ratio was first determined by Joule as 
772 foot-poimds to 1 B. T. TJ. The value was later more accurately 
determined by Bowland at Baltimore as 778, and this value is now 
generally accepted as correct. (777.6 foot-pounds of work = l 
B. T. IT. is sometimes used.) 

Therefore 1 B. T. U. is equivalent to 778 foot-pounds of work, 
or 778 foot-poimds of work are required to raise the temperature 
of 1 pound of water 1/180 of the temperature rise from 32* to 
212* P. 

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Mabinb and Naval Boilers 

Speoiflo Heat and Thermal Capacity. — ^The quantity of heat re- 
quired to raise 1 pound of a substance 1^ F. under given external 
conditions is known as the thermal capacity of the substance for 
these conditions. Thus^ if a quantity of heat, Q, is added to a body 
of weight M, causing a temperature rise from ^^ to ^,9 the quotient, 

-y equals the mean thermal capacity of the body. The 

mean thermal capacity of a body at some given temperature, com- 
pared with the mean thermal capacity of an equal weight of water 
at some standard temperature, is known as the specific heat of a 
body. The standard temperature is generally taken as 63.5^ F., 
and therefore 

c= specific heat of a substance = 

thermal capacity of substance 

at 63.5** F. 

thermal capacity of water 
at 63.5** F. 

Now, the thermal capacity of water at 63.5^ F. is equal to 1; 
therefore, the ratio of the heat absorbed divided by the rise in 
temperature due to this heat absorption is a measure of the mean 
specific heat of the substance. 

In general, the specific heat of a substance is variable, and changes 
with the temperature. The specific heat of water is not constant, 
and varies with the temperature as illustrated in the chart below. 







































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Heat, Heat Tbansper and Evaporation 169 

When dealing with gases and vapors, it is necessary to distinguish 
between specific heat at constant pressure and specific heat at con- 
stant volume. Thus, if a gas is heated in a closed vessel and is 
not allowed to change its volume, the heat absorbed divided by the 
temperature rise gives the mean specific heat at constant volume 
and is denoted by Co. Therefore, MOviU—ti) is equal to the heat 
absorbed and is a measure of the increase of the kinetic thermal 
energy of the gas. (^= weight of gas heated.) 

If, however, the gas be allowed to expand, due to the addition 
of the same quantity of heat, the pressure being kept constant, the 
rise in temperature will not be so great as in the first case, since part 
of the energy of the heat absorbed has been used to separate the 
molecules against their mutual attraction in order to increase the 
volume. From these considerations it is clear that, for a given in- 
crease in temperature, more heat is required to obtain the increase 
in temperature when the pressure is kept constant than when the 
volume is kept constant during the addition of heat. Therefore, c* 
is always less than Cp. For a so-called perfect gas, there ia a definite 

ratio between Cv and Cp given by ^ =Jk=1.4. 

The ratio is approached by many simple gases, such as H,, N,, 
Oj, etc. 

In general, for gases the specific heats are given by the following 

Cv=a+bt, Cp-a'+bX 

where a, a' and b, b' are constants depending on the gas, and ^ is the 

It has been found, however, that while the specific heats of 
simple and diatomic gases differ, their molecular specific heats are 
substantially the same. 

Molecular specific heat is the specific heat of a unit weight of gas 
multiplied by its molecular weight, and is usually given by the 
expressions mcv and mcp, where w= molecular weight. 

For simple gases, 

mcp=4.48 + 0.000667r, (1) 

mcp= 6.46 + 0.0006677, (2) 

where T is the absolute temperature. Therefore, to obtain the 
specific heat of a gas at a given temperature it ia only necessary to 
divide equation (1) or (2) by the molecular weight of the gas. 

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170 Marine and Nayal Boilbrb 

Carbon dioxide (CO,) and steam (or water vapor) do not follow 
the relations given in equations (1) and (2), but must be calcu- 
lated from equations (3) and (4) and (5) and (6), respectively. 
For CO,, 

Cv=0.12 +0.000066r, (3) 

c,= 0.166 + 0.0000667. (4) 

For steam (superheated), 

c«= 0.263 + 0.000133r, (5) 

Cp=0.374+0.000133r. (6) 

Examples: Eequired the specific heat of oxygen at 40* F., the 
pressure being constant. 
From equation (2), 

mc,=6.46 + 0.000667r. 

Cp=^^ [6.46 + 0.000667(40+460)], 

In a gaseous mixture it is assumed that, for a given rise in 
temperature, each constituent requires the same quantity of heat 
that it would require if separated from the mixture. Therefore, 

Q=Jf,c,^(i,-i,)+ilf,Ct,,(r,-rO+ ; 


Q = Mcv ( ^2 ■" ^1 ) i^ general. Therefore, since 

M^Cv^+M^Cv^^ .... =Mcv, 

where Jf=Jfi+-Jf2+Jf,+ . . . . , 

Example: A fine gas has the following constituents by weight: 

CO, 12.0 

CO 0.4 


N, 78.0 

Required the specific heat of the gas at constant pressure, at 440^ F. 

^ In the Appendix will be found tables of specific heats of Tmriom 

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Hbat, Ubat Tbaitsfbh and Etapobaiiok 171 

Apply formula (2) and (4). Then 7'= 440 +460 =900. 

Constituent. M. m. He,. 

CO, 12 12 [0.166+0.000066(900)] 

CO 0.4 28 1^ [6.46 +0.000667(900)] 

0, 9.6 32 |^[6.46 +0.000667(900)] 

N, 78 28 II [6.46 +0.000667(900)] 

ilf=TOO y,MCp= 3.1x7.06 =21.886" 

12 X .2244= 2.693 
.-. Cp for mixture= ^^=.2468. 

Heat Transfer. 

When two bodies of unequal temperatures are near each other^ 
there is a constant tendency to equalize the temperature by a trans- 
fer of heat from the hotter body to the colder body. Without such 
temperature difference no heat transfer between two bodies can be 
effected. Thus, the impelling farce in heat transfer is temperature 

This heat transfer takes place in three ways: by radiation, by 
conduction and by convection. 

Badiation of Heat. — ^A certain amount of heat which is given 
off by luminous and hot bodies follows the straight-line law for 
propagation of light. The amount of heat absorbed by a body ex- 
posed to such radiant heat has been foimd to depend upon the 
condition of the surface of the body and the difference of the fourth 
powers of the absolute temperatures of the radiating and absorbing 
bodies. Black bodies absorb a relatively larger proportion of heat 
than bodies having surfaces tending to reflect such heat. 

The effect of radiant heat in boiler furnaces is to increase con- 
siderably the rate of absorption of the heating surfaces exposed to 
the action of the radiant heat given off by the fuel bed and by such 
refractory brick surfaces as are heated to incandescence. The 
luminous particles in the gases give off a comparatively small quan- 
tity of radiant heat. 

Sadiant heat should not be confused with what has been termed 
'' radiation '* from hot surfaces such as hot cylinders^ boilers, casings 

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172 Marinb and Naval Boilbbs 

and steam pipes which are not well lagged. Such radiation is in 
reality a loss by convection to the surrounding particles of air, since 
the proportion of heat lost by true radiation is small unless the 
temperature difference ia high. 

Conduction of Heat. — ^The transfer of heat by conduction may be 
between the particles of the same body or between particles of dif- 
ferent bodies in contact. The heat in this case flows from particle 
to particle. In the case of the transfer of heat between particles of 
the same body, the transfer is said to be by internal conduction. 
The rate of heat transfer will depend upon the thermal conductivities 
of the substances. The thermal conductivities of various substances, 
liquid, solid and gaseous, have been determined by experiment and 
are tabulated below. 

B.T.U.'f per hour per 
square foot per degree 
Substance. F. per inch thick. 

Iron 443 at 82» P. 

Steel 279.5 at82»P. 

Zinc 443 at59»F. 

Copper 2080 at 32* P. 

Water 3.6 at65«P. 

Alcohol 1.4 at65«P. 

Petroleum 1.03 at65»F. 

Air '. .166at32»P. 

Nitrogen 152at32»P. 

Oxygen 163 at 32* P. 

It will be noted that the values for gases are very much lower 
than those for solids, and this fact has an extremely important 
bearing on the design and arrangement of heating surfaces for 
maximum efficiency. 

The resistance of gases to the transfer of heat by conduction makes 
it very difficult to effect a transfer of heat from a metal to a gas, or 
vice versa, where the gases are not in motion. This principle has 
been employed in lagging boilers by means of an air space between 
the inner and outer casings. 

Convection of Heat. — When the transfer of heat occurs between 
particles of gases or fluids, the whole mass is heated largely by 
convection ; that is, the particles nearest the source of heat become 
heated flrst and rise through the mass on account of their lesser 
density, being replaced by colder particles of greater densiiy, which 
in turn become heated and rise until the whole mass is at the same 
temperature. The currents set up in this manner are called con* 

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Hbat, Hbat Thansfbr and Evaporation 173 

yection currents and greatly accelerate the transmission of heat 
through gases and liquids. It is for this reason that hydrokineters 
are installed on Scotch boilers to increase the convection currents 
and thereby increase the rate at which the water in the boiler be- 
comes heated. 

Thus the necessity for the circulation of water in any boiler is 
at once apparent, but the greater necessity for a rapid flow of hot 
gases across the cooler heating surfaces of boilers has for many 
years been overlooked. 

Transmission of Heat into Heating Surfaces. — ^When the hot 
gases resulting from the combustion of coal or oil fuel pass along the 
heating surfaces of a boiler, a thin film of gas adheres to the sur- 
face and gives up some of its heat to the metal. This cool film of 
gas, however, remains in contact with the metal and prevents the 
hotter gases from coming in contact with the heating surface and 
transmitting their heat to the metal. Since the resistance of this 
thin film of gas to the transmission of heat by conduction ia very 
high, it is evident that the greatest proportion of heat losses from 
hot gases to heating surfaces is due to this gas film. The film can be 
removed only by increased circulation of the gases over the heating 
surface. The increased speed results in a scouring action which 
removes to some extent the cool film. 

In like manner, the water on the other side of the tubes, in passing, 
leaves a thin film adhering to the tubes, which offers a high resist- 
ance to the flow of heat from the tubes to the water. This film of 
water, however, would offer only about one-tenth as much resist- 
ance to the fiow of heat as would a gas film of equal thickness. It is 
evident, therefore, from a glance at the table of thermal conductivi- 
ties (page 172), that the controlling resistance to heat absorption lies 
on the gas side of the metal, and before any considerable improve- 
ment can be made in heating surface efficiency by increased circula- 
tion of water in the boiler, the controlling resistance (t. e., resist- 
ance of the gas film) must be reduced. 

The fiow of heat from the gases to the water is therefore as 
follows : From the gases to the gas film by convection ; through the 
gas film to the metal by conduction ; through the metal by conduc- 
tion ; from the metal to the water film by conduction, and from the 
water film to the water by convection. 

If the tubes are covered with soot deposits on the gas side or with 
scale on the water side, the resistance to the fiow of heat by conduc- 

Digitized by 


174 Marine and Naval Boilbrs 

tion will be still further increased. Hence, the necessity for keeping 
the tubes free from soot and scale is apparent. 

The effect of scale, or deposits of insoluble substances on the 
water side of the tubes has a still further effect. The metal of the 
tube takes the temperature of the medium opposite to the con- 
trolling resistance, so that, in general, with clean tubes, it will take 
the temperature of the water. If, however, a thick scale, having a 
high thermal resistance, ia allowed to accumulate on the water side, 
the controlling resistance may pass to the water side and the tube 
will take the temperature of tiie gases. This will cause severe over- 
heating of the metal, which may result in burning out the tube. 


Formation of Steam. — ^When fires are started in the furnaces of a 
boiler, with the safety-valves open, the particles of water in contact 
with the heating surfaces become heated, expand, and rise to the 
surface, being replaced by the cooler particles from above. As the 
heating, which we can measure practically by a thermometer in the 
water, goes on, the whole mass is raised in temperature until the 
boiler is full of boiling water, giving off vapor or steam when 212* F. 
is reached. This point, called the boiling point, will always corre- 
spond to this temperature when the water is under atmospheric 
pressure, 14.7 pounds to the square inch. If, under these conditions, 
the application of heat is continued, the thermometer remains 
stationary at 212*" F. until all of the water has been evaporated into 
steam of atmospheric pressure and a temperature of 212° F. It is 
apparent, therefore, that a large amount of heat has been absorbed 
by the water in changing it from liquid into vapor or steam. 

If the safeiy-valves are closed when the boiling point is reached, 
there is, at that instant, a boiler full of water at a temperature of 
212° F. and under a pressure of 14.7 pounds per square inch, and 
the steam gage shows the pointer at zero, or no pressure by gage. 

The safety-valves being closed, the thermometer will show a 
gradual increase in the temperature of the water as the absorption 
of heat from the hot gases continues. If the steam gage is now 
observed, it will be seen that the pointer has left the zero mark and 
is rising, showing that there is a pressure in the boiler. This 
pressure is caused by confining the steam as it is formed in the 
steam space of the boiler, and, as we have started with the atmos- 
pheric pressure in it, the reading of Hhe pressure, as shown by the 

Digitized by 


Heat, Hbat Teansfbb and Evaporation 175 

steam gage> must be increased by 14.7 pounds to give the totals oi 
absolute pressure. 

NoWy suppose that when the absolute pressure has reached 80 
pounds, or 66.3 poimds by gage (at which pressure the temperature 
is 312** P.), the stop-valves are opened and the engine is started 
and ran at such speed as to keep the pressure in the boiler constant. 
Under these conditions it is found that while heat is being absorbed 
continuously for the production of steam of 80 pounds pressure, 
the temperature of the water remains at 312** F., instead of at 
212** P., as when the pressure was that of the atmosphere only. 

Again, if the conditions are fixed to produce steam constantly at 
160 pounds absolute, or 145.3 pounds by gage, the temperature of 
the water remains at 363.6** F. 

Boiling Point. — From the above examples it is seen that the tem* 
perature at which the water is converted into steam, or its boiling 
point, does not remain constant, but that it bears some relation to 
the pressure. If the process had been started with a pressure of 80 
pounds absolute on the surface of the water, no boiling would have 
taken place until the temperature of the water had been raised to 
312** F. There is, then, a certain boiling point for each pressure, 
which increases with the pressure. The relation between the tem- 
perature and the pressure has been determined experimentally, 
and is given in Table I, at the end of this book. 

As the boiling point, or temperature of the steam, and other data 
are needed lisually for a certain pressure as read on the steam gage, 
it must not be forgotten that the temperature depends upon tiie 
absolute pressure, or the pressure above a perfect vacuum. Tables 
I and II are made out for absolute pressures only, so that, when 
using them, 14.7 pounds must be added to the reading of the steam 

In Table II the data have been arranged for pressures below the 
atmosphere, in inches of mercury. 

The boiling point of water is increased by salts dissolved in it, as 
in sea water, but not by bodies in mechanical suspension only, as 
sand in river water. For sea water, which contains about 1/32 part 
of solid matter, the boiling point is 213.2** F. under atmospheric 
pressure ; and this is raised as the proportion of salt or dissolved solid 
matter increases, so that, with a concentration of 4/32, the boiling 
point, under atmospheric pressure, would be about 217** F. But it 
has been proved by experiment that the steam produced from any 

Digitized by 


176 Marine and Naval Boilbbs 

saline solntion is that of pure water (this fact being taken advantage 
of in distilling of fresh water), and also that the temperature of the 
steam formed at higher pressures is the same as that of steam formed 
from fresh water at the same pressure. 

Sensible Heat. — From the explanation of the formation of steam 
previously given, it is apparent that not all of the heat expended in 
raising the temperature of the water to the boiling point, and in 
evaporating it at any pressure, is recorded by the thermpmeter as 
rise of temperature. The quantity. of heat which the thermometet 
measures is called the sensible heat. The thermometer does not 
measure the exact amount of sensible heat, on account of the varia- 
tion in the specific heat of water with change of temperature. The 
exact value of the sensible heat of water may be picked out from 
the steam tables for any required temperature. 

Latent Heat. — ^When water is allowed to boil at any pressure, any 
further addition of heat is expended in changing the water to steam, 
without increase of temperature until all the water present has been 
converted into steam. The heat required to change the ''state'' 
of a unit weight (1 pound) of a body is called the iatent heat of the 
substance. This latent heat, in the case of steam, consists of two 
parts, called respectively the external and internal latent heat. The 
internal latent heat is that expended in overcoming the mutual 
attraction of the molecules of water, which resist change of state to 
steam, whereas the external latent heat is equivalent to the work 
done in changing the volume at constant pressure during the trans- 
formation to steam. The external latent heat is measured as 
follows : 

External latent heat=-y (v— t/), 

where p= absolute pressure in pounds per square foot, t;= specific 
volume of saturated steam, t;'= volume of 1 pound of water, and 
i7'=Joule^s equivalent=778. In the steam tables this term is de- 
noted by 


where p is internal latent heat, and A= y. (i;'=ihe volume of 1 

pound of water, which is negligible in comparison with the volume 
of steam.) Then the total latent heat of vaporization of steam at 
any pressure and corresponding temperature is the sum of the 
internal and external latent heat. The latent heat of Vaporization 

Digitized by 


Heat^ Hbat Tbansfek and Eyapobation 177 

of steam decreases with increase of temperature and pressure. 
Therefore^ all the latent heat which goes to change the water into 
steam^ while not evidenced by a change of temperature during the 
process, is still latent in the steam as potential thermal energy, and 
is capable of being transformed into mechanical energy exactly as 
potential mechanical energy may be transformed into kinetic me- 
chanical energy. 

Total Heat of Steam. — The total heat of steam at any definite 
pressure and temperature is the number of B. T. IT. necessary to 
raise a quantity of water from 32** P. to the temperature required, 
and to change it to steam at that temperature and pressure. When 
total heat is referred to in engineering, it means the total heat in a 
quantity of steam above the arbitrary zero, which is taken at 32® P. 
It is expressed by the equation formula 


where L is latent heat and 8 is sensible heat, and is the sum of 
latent and sensible heats at that temperature. Thus the total heat 
of 10 pounds of dry steam at 212'' F. equals 10 times the total heat 
of 1 pound of dry steam at 212** P. The numerical value of the 
total heat of 1 pound of steam at any given temperature and pres- 
sure may be obtained from the steam tables, or may be computed 
from the following empirical formula when no steam tables are 

i7= total heat of 1 pound of steam 
= 1160.3 + .3745(i-212)-.00065(^-212)^ 

Prom an inspection of the steam tables, and the above formula, 
it is evident that the total heat of a pound of steam increases with 
an increase of temperature. 

Saturated Steam. — ^When a quantity of water is allowed to boil 
and steam is formed in contact with the water, this steam is normally 
dry and contains no particles of water held in suspension with it. 
Steam in this condition is said to be saturated, and has a definite 
volume and pressure at any given temperature. If any heat is 
abstracted from the steam while it is in this state, some of it will 
condense. Any increase in pressure will likewise cause a partial 
condensation of the steam. If the pressure is reduced, some of the 
water with which it is in contact will flash into steam. At a given 
temperature, saturated steam has the greatest density and pressure 
possible to remain a dry vapor. 

Digitized by 


178 Marine akd Naval Boilers 

Wet Steam. — If, for any reason, such as loss of heat from saturated 
steam, some of the steam is condensed to water and these particles 
of water remain suspended in the steam, the resulting mixture is 
called wet steam. Wet steam is sometimes formed in a boiler by 
the violent ebullition of water, causing some of the particles to 
be carried oflE in the steam. In well-designed boilers, the quantity 
of this entrained water rarely exceeds 1^. In a definite weight of 
wet steam, the percentage of dry steam in the total quantity of 
moisture and dry steam is termed the quality of the steam. Thus 
when a pound of water is converted into wet steam of quality .98 
there is by weight 98^ of dry steam and 2^ of moisture in the steam. 

Total Heat of Wet Steam. — Let Q represent the quality of the 
steam. Then, from one pound of water, Q parts will be changed 
to steam and {l — Q) parts will remain water. Therefore, the total 
heat of the steam will equal 

where L= latent heat and iS = sensible heat, or heat of the liquid, 
for the given temperature. 

Example: Find H, L and 8 for dry steam, when the steam gage 
shows 135.3 pounds, the temperature of the feed water being 32** F. 

From the table, L= 863.2, 5=330.2, and H therefore =863.2 4- 
330.2 = 1193.4 B. T. U. 

Now suppose that, instead of dry steam, the quality of the steam 
is .97. Then 

ir=.97L + iS=.97x863.2 + 330.2 = 116r.5 B. T. U. 

Superheated Steam. — If a quantity of steam is removed from con- 
tact with the water from which it was generated, and additional 
heat is put into it, the result will be superheated steam. 

If the volume of steam is kept constant by confining it in a closed 
vessel, the pressure and temperature will rise with the addition of 
heat; whereas, if the pressure is kept constant, the volume and tem- 
perature will both become greater than the volume and temperature 
at saturation. The amount of increase in temperature above the 
temperature of saturation at a given pressure is the number of 
degrees of superheat. 

Superheated steam approaches the condition of a perfect gas, 
particularly with high degrees of superheat, and therefore follows 
very nearly Boyle^s Law for variations of temperature, pressure and 

Digitized by 


Heat, Heat Transfer and Evaporation 179 

Boyle's Law: '^ As long as its temperature remains the same, the 
pressure of a quantity of gas is inversely proportional to its volume/' 

The specific heat of superheated steam varies with the tempera- 
ture, and, in general, has an average value of nearly .48 for low 
degrees of superheat. This value (.48) is close enough for rough 
calculations where only moderate temperature and low degrees of 
superheat are used. The total heat of superheated steam is given 
by the following equation : 


ff''= total heat of superheated steam, 
5"= total heat of dry (saturated) steam at temperature t. 
(7'p=mean specific heat, at constant pressure of superheated steam 
for the temperature range. 

r= temperature of the superheated steam. 

^= temperature of saturated steam at pressure p. 

{G'p may be taken roughly at .48.) 

Heat Bequired to Produce Steam from Feed Temperature. — ^In 
Tables I and II the calculations are based on a temperature of 32** P. 
for the feed water. But, in practice, this temperature is always 
higher, and therefore less heat will be required to raise the feed 
water from its entering temperature to that corresponding to the 

Example: How many thermal imits are required to produce 
steam at a pressure of 135.3 pounds by gage, the feed water being 
admitted at 160** P. ? Quality of steam .97. 

As before, 8, or the heat of the water corresponding to a pressure 
of 150 pounds absolute, is 330.2. But the heat of the feed water 8' 
corresponding to a temperature of 160** P. is 127.86 B. T. U. 
Therefore, to raise the feed water to the boiling point, 330.2—127.86 
=202.34 B. T. U. are required. 8—8' may be taken as the new 
value of 8. QL is .97 x 863.2 = 837.3. 

Therefore, there will be required under these conditions only 
837.3 + 202.34=1039.64 B. T. U. 

Actual and Equivalent Evaporation. — Taking the heating value 
of one poimd of average steaming coal as 14,162 B. T. U., and as- 
suming that the boiler transfers .68 of the heat of the coal to the 
water, each pound of coal burned gives 14,162 x. 68 = 9630.2 units 
to the water. But, to convert one pound of water from 160** P. into 
steam of quality .97 and a pressure of 135.3 pounds by gage, only 

Digitized by 


180 Mabinb akd Natal Boilebs 

1039.64 units are required. Therefore, 9630.2 -r- 1039.64= 9.26 
pounds of water were vaporized by each pound of this coal under the 
above conditions, or the actual evaporation is 9.26 pounds. 

The theoretical evaporative power of the fuel, from and at 212** P., 
is 14.59 pounds ; and, as the efficiency of the boiler is ,68, the real 
evaporative power of the fuel, from and at 212** P., is 14.59 x .68= 
9.92 pounds. This result would have been obtained directly by 
dividing 9630.2, the heat units absorbed by the water, by 970.4, the 
heat units required to convert 1 pound of water from a feed tempera- 
ture of 212** P. into dry steam of the same temperature.* 

That is, the evaporation of 9.26 pounds of water xmder the actual 
conditions is equivalent to the evaporation of 9.92 pounds from and 
at 212** P.; or, using the usual expression, the equivalent evapora- 
tion from and at 212** P. is 9.92 pounds. 

Factor of Evaporation. — ^This is the ratio of the number of heat 
units in 1 pound of steam at the given pressure, and calculated from 
the temperature t of the feed water, to the number required to 
vaporize 1 pound of water into dry steam from and at 212** P.; or, 

. ff-S' ^ QL +8-S' 
^ 970.4 " 970.4 ' 

S' being the heat units in the feed water at the temperature t 

For the above example, under total heat of wet steam, 1193.2 — 
127.86 -=- 970.4 = 1.098 is the factor of evaporation. 

Tables are published giving the factors of evaporation for various 
steam pressures and temperatures of feed water. But, as these 
assume that the steam produced in every case is dry, the method 
given above must be followed when Q is other than unity, or, if 
the factors are used, Q must be corrected as will be explained under 
« Boiler Tests.'* 

The various steps in the transference of the heat energy of the 
fuel to the steam have been shown, and the energy of this steam is 
now ready to do useful work in the various engines on board. 

* The latest authoritative steam tables (Marks and Davis) give this 
ralue as 970.4. 

Digitized by 



Combustion, in its broadest sense^ is any chemical act that is 
accompanied by the evolution of heat. Ordinarily, it is restricted in 
meaning to the chemical imion of other substances with oxygen, 
resulting in the production of heat. 

A combustible substance is one which, when raised to its tempera- 
ture of ignition, combines readily with the oxygen in the air, pro- 
ducing heat. 

The Chemistry of Fuel and Combustion. 
The five principal elements found in ordinary fuel are : 

Symbol. Approximate 
atomic weight. 

Carbon C 12 

Hydrogen H 1 

Oxygen O 16 

Nitrogen N 14 

Sulphur S 82 

The atomic weights are the relative proportions, by weight, in 
which the elements combine with each otiier to form definite chem- 
ical compounds. Thus, 

2H + 0=H,0, 

2 lbs H4-16 lbs. = 18 lbs. H,0= water. 

12 lbs. G + 16 lbs. = 28 lbs. GO = carbon monoxide, 

12 lbs. C + 32 lbs. = 44 lbs. GO, = carbon dioxide, 

12 lbs. G+ 4 lbs. H= 16 lbs. GH4= methane (marsh gas) . 

Composition of Air. 

Ordinary air is composed principally of oxygen and nitrogen 
with varying amounts of water vapor held in suspension. These 
constituents do not exist in air as a chemical compound, but simply 
as a mechanical mixture. Therefore, the oxygen present in the 
air is free to combine with other elements to support combustion. 

Digitized by 


182 Marinb and Naval Boilbrs 

For practical purposes the composition of air may be taken as 77jf 
nitrogen and 23^ oxygen by weighty and 79^ nitrogen and 21^ 
oxygen by volume. 

The amount of moisture (or water vapor) in the air is determined 
by the relative humidity of the atmosphere. This relative humid- 
ity is determined by tables in which the arguments are the readings 
of the wet- and dry-bulb thermometer, or by instnmients con- 
structed to give the temperature of the dew-point for any existing 
atmospheric conditions. 

Humidity is the ratio of the moisture contained in the air at a 
given temperature to the amount it is capable of containing at that 
temperature when saturated. It is expressed as a percentage. 

General Characteristics of the Principal Elements in Combustibles. 

Hydrogen. — Hydrogen is a very light combustible gas. When it 
combines with oxygen, the result is the liberation of 62,032 B. T; U. 
per pound of hydrogen burned. The result of this combustion is 
the formation of HjO in the form of water vapor or steam, some 
of the heat units resulting from combustion going to change the 
water to steam. This results in a loss of 970.4 B. T. XJ. for every 
pound of HjO thus generated at atmospheric pressure. This appar- 
ent loss of heat gives rise to the double heating value of hydrogen 
as usually tabulated ; viz., the higher and the lower. 

Oxygen. — Oxygen is 16 times as heavy as hydrogen and is the 
universal supporter of combustion. Without oxygen there can be no 

Nitrogen. — Nitrogen is an invisible gas, 14 times as heavy as 
hydrogen. It has so little chemical aflSnity for other elements that 
it will not combine with them easily by the ordinary chemical 
methods. It is the diluent of oxygen in the air, restraining the 
activity of the oxygen and causing combustion and corrosion to be 
less rapid than in pure oxygen. 

Carbon. — Carbon exists (a) in the pure state, in diamond, coal 
and graphite; (b) combined with hydrogen, in oils, tars and gases; 
(c) combined with hydrogen and oxygen, in the whole range of 
vegetable products. It is the principal constituent of coal and of 
most other fuels, whether in the solid, in the liquid, or in the gaseous 

Sulphur. — ^A trace of sulphur is found in most coals, varying in 
amounts from .10^ to about 3.0^. It has a low heating value (4050) , 
and has the further disadvantage of combining readily with any 

Digitized by 




moisture^ forming sulphuric acid^ which is injurious to the boiler 
material. Coal relatively high in sulphur is not accepted by the 
Nayy for steaming coal. 

Heating Value of Combustibles. 

In general^ chemical reactions are accompanied by the absorption 
or evolution of heat. When a combustible unites with oxygen, the 
process is characterized by the evolution of a considerable quantity 
of heat. The heat thus evolved per imit weight (pound) of com- 
bustible is called the heating value of the substance. Hydrogen, 
and compounds containing hydrogen, have two heating values, called 
respectively the higher and the lower. This is due to the fact that 
the result of the union of hydrogen and oxygen may be either water 
or steam. If the product is steam, then the heat necessary to keep 
it in the form of a vapor is not set free and the lower heating value 
must be used. If, however, the vapor condenses, the heat of vapori- 
zation and some of the sensible heat of the liquid is recovered, yield- 
ing the higher heating value. 

The following table gives the heating values of various substances. 

Heatino Values of 1 Pound or Vabious Pure Substances 
Burned in Oxygen. 

Substance. Burned to generaYed 

Hydrogen Liquid water (H,0) . 62032 

Hydrogen Liquid water (H,0) . 61816 

C (wood charcoal) . .CO 14544 

C coal CO, 14647 

C (diamond) .CO, 14146 

C (black diamond) . .CO, 14150 

C (graphite) CO 14222 

C CO 4451 

CO. per unit of CO. . .CO, 4325 

CO, per unit of CO. . .CO, 4293 

CO, per unit of C. . . .CO, 10093 

CH4 CO,andH,0 23513 

CH, CO,andH,0 23616 

Cyi CO,andH,0 21523 

CH4 CO,andH,0 21344 

C,H, C0,andH,0 18196 

C JI„ benzole gas . . . .CO, and H,0 17847 

C,H„ benzole gas CO, and H,0 18184 

Sulphur SO, 4060 


Favre ft Silbermann. 


Favre ft Silbermann. 





Favre ft Silbermann. 

Favre ft Silbermann. 


Favre ft Silbermann. 

Favre ft Silbermann. 



Favre ft Silbermann. 


Favre ft Silbermann. 


N. W. Lord. 

The heating value of a mixture is determined from the heating 
values of the several constituents. If the percentage by weight of the 

Digitized by 


184 Mabinb and Naval Boilebs 

constituents is denoted by M^, M^, M^, . . . . , and their corresponding 

heating values per pound by H^, Hi, H^, , the heating value of 

the mixture Hm niay be determined as follows : 

where M= 100j<= 100. 

Example: Bequired the heating value of the fuel having the con- 
stituents by weight as given below : 

Constituent. <%b7wefffbt. H. MH, 

Ha 4.8 62032 297753.6 

C 83.5 14644 1214424.0 

0, 4.2 neglected 

N 1.3 non-combustible 

S 7 4050 2835.0 

Ash 5.5 non-combustible 

SJTif= 1516012.6 
.•.JT«= 15150 B.T.U. 

This gives a slightly higher value than is found by experiment. 

Dulong's Formula. — Dulong's Formula is derived in the manner 
shown above, but assumes that the oxygen in the fuel has already 
combined with the hydrogen in the fuel and the heat so generated 

lost; therefore the term (H — --) appears in the formula, since the 


combining proportions of H and are as 1 to 8 by weight. 
The formula is as follows : 

Heat value in B. T. U.= jj^ [14,600 C + 62,000 (H-^)], 

where C, H and are the percentages by weight of carbon, hydrogen 
and oxygen in the fuel as determined by analysis. 

Air for Combustion. 
The oxygen required for the complete combustion of a given fuel 
is determined from the equation of its reaction. For example: 

or, taking the atomic weights, 

12 lbs. C + 32 lbs. 0=44 lbs. CO,, 

lib. C+ j|lbs. 0=j|lbs. CO,, 

Digitized by 


Combustion 185 

• To obtain 1 pound of oxygen, -^^ pounds of air are necessary, 

since each pound of air contains .23 oxygen by weight. Therefore, 
in the foregoing example: 

32 9 1 
.9 lb. C requires ^ X w q X -oo ^^' of ^*^ ^ ^^ complete combustion. 

If the composition by weight of a fuel is obtained from the ulti- 
mate analysis, the air required for complete combustion may be 
calculated as indicated below for a sample of Pocahontas coal : 

Constituent. % by weight. 

C 83.6 

H, 4.8 

0, 4.2 

Sj 0.7 Generally neglected in practice. 

. * _* Inon-combnstible. 

Ash 6.6 J 


.836 lb. C requires -f ?- X ~3 = 9-68 

.048 lb. H, requires '^l x 8 = 1.67 


The above method does not take into account the oxygen m the 
fuel to start with. This is generally considered as combining with 

the H in the coal, and the H value is reduced by -^ > since the com- 
bining proportion of H and is as 1 to 8. Then the corrected 
value of H is 

.048--^!- =.048 -.0063 = .0427, 


and the correct solution of the problem is : 

Lbs. air. 

.836 lb. C requires — J4 X -?o^ = 9.68 

.0427 lb. H requires -"tV^ X 8 = 1.485 


Digitized by 


186 Marine and Naval Boilebs 

Therefore^ one pound of the fuel having the analysis given above 
requires 11.166 pounds of air for its complete combustion. In 
practice, however, coal can never be burned completely without more 
air than is theoretically required, the excess per cent being termed 
the excess air. 

Ultimate Analysis. 

The ultimate analysis of a coal is the quantitative chemical 
analysis of a representative sample of the coal. This analysis should 
be performed only by an expert chemist, as it requires great skill. 
The ultimate analysis of any coal mined in the United States may 
be obtained from the tables issued by the Bureau of Mines. 

The coal most commonly used in the United States Navy is semi- 
bituminous coal. The ultimate chemical analysis of this coal shows 
its constituents to be carbon, hydrogen, oxygen, sulphur, nitrogen, 
and ash. The ash is composed of non-combustible solids, including 
slate, etc., and has the particular advantage of not being readily 
fused at high furnace temperatures. This coal is therefore relatively 
free from a tendency to clinker unless fires are carried very thick. 

Although the ultimate analysis will determine the percentage oi 
each of the constituents of the coal, nothing is definitely known 
regarding the manner in which these constituents are combined 
among themselves. It is probable, however, that some very complex 
chemical compounds exist in the coal, some of which are driven off 
in gaaeous form when the coal is heated. The gases thus formed are 
termed volatiles. The amount of volatile matter distilled from the 
coal will depend upon the temperature at which distillation occurs. 
In general, the higher the temperature the greater will be the amount 
of volatiles and the more complex will be the chemical nature of the 
products. The volatile matter from semi-bituminous coal consists 
of hydrocarbons, ammonia and coal tar products. The lighter 
hydrocarbons such as methane, CH^, burn readily. The heavier 
distillates resulting from rapid heating at a high temperature are 
more complex, have a high ignition temperature, and are, therefore, 
much more difficult to bum. 

The residue after the volatiles are driven off consists of what is 
termed fixed carbon and ash. This fixed carbon burns to CO and 
CO,, the relative proportions of each depending upon the thickness 
of the fuel bed, the temperature, and the amount of air supplied. 

Digitized by 


Combustion 187 

Proximate Analysis. 

The proximate analysis is used to determine the percentage of 
moisture, volatile matter, fixed carbon and ash in the coal. It is 
carried out as follows, viz. : 

(1) From a weighed sample, say a gram of coal, the moisture 
is first driven ofif by heating it to a temperature of from 260® to 
300** P. for a given time. The sample is then quickly reweighed, the 
ratio, loss of weight to the original weight, being the percentage of 

(2) The volatile matter is then driven oflE by heating the sample 
in a closed crucible to a red heat for a short time. It is then re- 
weighed and the percentage of loss of weight is the percentage of 
volatile matter distilled off. 

(3) The carbon is burned out of the remaining coke by keeping 
it at white heat with a plentiful supply of air until nothing is left 
but ash. The ash is weighed and the percentage of fixed carbon 
and ash thereby determined. 

It must be remembered, however, that the amount and quality of 
the volatiles driven off in the proximate analysis are relative only, 
and do not necessarily determine the conditions existing in a hand- 
fired furnace where the coal is subjected to destructive distillation 
at high temperatures. 

Classification of Coal. 

Coals are classified according to the relative percentages of carbon 
and volatile matter contained in the combustible portions, anthracite 
showing the lowest percentage, and bituminous the highest per- 
centage, of volatile matter on analysis. 

Digitized by 



Mabinb and Naval Boilebs 

Composition of Coal. 

Chimioal O0MPO8ITION or Vabious Stcauinq Coals and Liquid Fubls, thbib Biatiito 
Valuis, and Volumi Occupibd bt Oni Ton. 

Name .of fuel and country 
from which obtained. 

Anthr, and Semi-Anthr. 

I^ennaylvania, av Am. 

Lehigh, Pa " 

Drifton, Pa " 

Nixon'a Navigation Walea 

Powell's Dufiryn '* 

Is^re France 

Semi' Bituminous. 


Pocahontas, W. Va. 
New River, W. Va.. 
George's Creek, Md. 

Clearfield, Pa 

Cardiff, av Wales 

Newcastle Engl. 


Pittsburgh steaming Am. 

Pratt seam, Ala 

Washington State, av. 

Br. Columbia, av 

Scotch, av 

Miike Japan 

Chilean, av 

Batan Island P. I. 

Patent Fuel. 

British, av 

Warlich's Engl, 

French, av 

Liquid Fuel. 

Pennsylvania, kerosene 

Pratt's fuel oil. Pa 

Eagle fuel oil. Pa 

Beaumont, Tex., distilled 

Kern River, Cal., distilled.... 

Astatki, Baku, * Russ 

Borneo, crude 

Burma, refuse* 

Ultimate analysis. 

.5 4.8 4.2 1.8 

83.6, 4.71 4.5 1.6 

81.0 4.9 4.6 2.2 

80.2 6.1 4.7i 1.4 

88.8 4.8 4.r 1.0 

82.4 5.5 6.8 1.6 1.8 

76.5 5.2 

8.1 1.4' 1.2 

78.6 5.6i 9.7 1.0 
75.0, 5.8 ? 1.1 
63.6 5.4,14.8 .8 

88.4 5.0 2.8 
90.0 5.6. 


4 10.3 

68.831.5 8.5 1.2 
57.782-.8 8.3 1.2 

1.1, 4.1 
8.2 12.0? 
2.5, 12.9 
.5 45. 

56.533.9 8.1 

1.1, 1.8 
... 1.6 




40. j 5.5 





6.3 (Incl.fmparitlea) 
1.6....' ...' 


.852,200 268 
.849 249 296 
.926216 240 
.962228 [258 




1 14,580 

12 ism 





15,000< 84.4 

16.495 .... 

15,000 84.5 

,000 J 



* After sulphur and other impurities have been removed. 

Digitized by 


Combustion 189 

Combustion of Coal in Fumaces. 

When a fresh charge of green coal is thrown on the incandescent 
fuel bed, the first process is the evaporation of the moisture in the 
coal. This is essentially a cooling process, since heat must be 
absorbed by the moisture in changing its state from water to steam, 
and such heat is abstracted from that evolved by the incan- 
descent fuel. After the moisture has been driven off, the distillation 
of volatiles begins, and since the process occurs rapidly and at a high 
temperature, the volatiles consist of the heavy hydrocarbons and 
coal tar products. These volatiles require a large amoimt of air 
and a high temperature for complete combustion, but in hand-fired 
fumaces the fresh charge of coal falls between the interstices of the 
incandescent fuel bed, blocking the supply of air at the very time it 
is most needed. Therefore, volatile matter combined with the CO 
and CO2 from the incandescent fuel may travel through the com- 
bustion space without coming in contact with sufiicient air for com- 
bustion until after it has been chilled below the ignition temperature 
by the relatively cooler heating surfaces. The unburned coal tar 
globules and carbon particles are deposited upon the heating sur- 
faces as soot or pass out through the uptake as a dense smoke, giving 
visible evidence of poor furnace conditions. 

The distillation of the heavier volatiles takes ordinarily about 
three minutes, after which the residue bums as fixed carbon, dis- 
tilling off only a slight amoimt of volatile matter. 

When air first comes in contact with this incandescent carbon, 
the oxygen unites with it to form CO,. If the fuel bed is thick, how- 
ever, and the CO, remains for a relatively long time at a high tem- 
perature in contact with the incandescent carbon, the CO, will unite 
with more carbon to form CO. The formation of CO is particularly 
liable to occur if any moisture is present in the air, such moisture 
reacting with the incandescent carbon; thus: 

H20 + C=C0 + H,. 

The formation of CO as here described requires heat to bring 
about the reaction, and thus cools the furnace. The presence of 
any CO is undesirable, as its heating value is only about 30}^ of that 
of CO,. 

The CO thus mixed with CO2 in the combustion space of the 
furnace may be reconverted into CO, by bringing its particles into 
intimate contact with air at a sufficiently high temperature. 

Digitized by 


190 Marine and Naval Boilbbs 

It has been founds however^ that excess air admitted above the 
grate will not assist in the combustion of the gases unless some 
special mixing device is employed. Experiments show that streams 
of combustible gas and air will travel side by side without burning 
except where they actually make contact, imless some baflling ar- 
rangement forces them to mix. Up to the present time such baffles 
have not been a practical success on account of the resulting high 
temperatures which fuse ordinary fire brick. The excess air ad- 
mitted over the grate for the purpose of completely burning the 
volatiles serves only to chill the gases and results in a loss of 

The ash which results from the combustion of coal falls through 
the grate bars into the ash pit, or fuses, forming clinkers. Clinkers 
are particularly liable to form with coals having an ash which fuses 
at temperatures around 2400° F., and when heavy fires are carried. 
The ash of some coals is more liable to fuse than others, but the 
tendency of an ash to fuse cannot be determined by a chemical 
analysis of the constituents. The tendency of an ash to clinker may 
make all the difference between an excellent steaming coal and a 
poor one. 

Furnace Temperatures. — From the above, it is apparent that a 
large proportion of the heating value of the fuel is due to the volatile 
matter of the coal, and the boiler furnace may be regarded as a gas 
producer. The problem then becomes one of burning these gases 
completely with the minimum excess air. 

llieoretically furnace temperatures might be computed by the fol- 
lowing formula, viz. : 

r=rise in temperature {t) + temperature of air in fire room (t^), 

T—ij. i _ B. T. TT. genera ted by fuel 

~" ^ "" weight of gases x specific heat of gases * 
Such computations are of no practical value, since the theoretical 
temperatures are generally about twice as large as those actually 
attained, for two reasons: (1) Heat is being absorbed by radia- 
tion and convection during the process of combustion; (2) the dis- 
sociation temperatures of some gases are reached, the heat going to 
break down the chemical compounds without further increase of 

Digitized by 


Combustion 191 

In practice^ furnace temperatures with semi-bituminous coals 
vary from 2000** to about 3000° P., being lowest right after a fresh 
charge is fired. 

Furnace Efficiency. — ^The efficiency of the furnace is the ratio of 
the heat actually generated to the heat in the combustible (fuel free 
from ash). There is no practical method of determining the 
amount of heat actually generated^ since the temperature of the 
gases is not necessarily a function of the furnace efiBciency, and 
therefore such determination must be made indirectly. 

The furnace losses are: 

(1) Loss due to incomplete combustion of fuel. 

(2) Loss due to radiation and conduction. 

(3) Loss due to excess air. 

(4) Loss due to unbumed combustible falling through the grate. 

(5) Loss due to moisture in coal and air, requiring a certain 

amount of heat to convert the water into steam. 

The losses due to incomplete combustion may be approximated 
from the analysis of flue gas, but it must be remembered that the 
volumetric analysis does not (except in laboratory work) show the 
loss due to unbumed hydrocarbons, etc. It has been found, how- 
ever, that when, upon analysis, CO is present in a flue gas, it is 
generally accompanied by some CH^, CjHio, etc.; therefore rela- 
tively large amounts of CO (over 0.1}^) should be regarded as indi 
eating poor furnace conditions. 

Losses due to radiation and conduction generally amount to about 
4j^ of the total heat balance in the B. & W. boiler. (See Appendix.) 

Losses due to excess air may be serious when it exceeds that 
necessary for complete combustion, on account of the cooling effect 
of this unnecessary air. Heat evolved from the combustion of . 
gases must then go to heating up large quantities of nitrogen intro- 
duced with the excess air, causing a larger proportion to be lost in 
the stack gases. 

The loss due to combustible falling through the grate is generally 
small with properly designed grate bars. In practice it amounts to 
about 0.6j< to 1^ of the total heat balance. When fires are cleaned, 
a larger amount may be lost, being hauled out with the clinkers. 

Loss due to moisture in fuel and air depends upon the atmospheric 
conditions and the moisture in coal. This loss is due to heat re- 
quired to convert water to steam and superheat' this steam to the 
smoke-stack gas temperature. This loss rarely exceeds 4^, 

Digitized by 


192 Marine and Naval Boilbbs 

As the rate of steaming increases (i. e., more coal burned per 
square foot of grate surface per hour), the furnace efficiency de- 
creases. This falling off of efficiency is due to the fact that at high 
steaming rates the combustion ot the gases evolved from the fuel 
localizes further and further away from the fuel bed. As the gases 
are being evolved in larger quantities, more space and more time 
are required for the proper mixture of these gases with the necessary 
air for combustion. The gases are forced through the combustion 
space faster, and do not have time to mix properly with the air 
before striking the cooler heating surfaces and becoming chilled 
below their ignition temperatures. The result is a larger loss due 
to the incomplete combustion of carbon and hydrocarbons to CO. 

Amount of Air Bequired Over the Grate. — ^When coal is first 
thrown on the fire, a large amount of volatile gases are distilled off, 
requiring a large amount of air for their complete combustion. The 
amount of volatiles and the duration of this process of distillation 
depend upon the coal and the furnace temperature, being greater 
for bituminous than for anthracite coals. The usual practice has 
been to admit air over the grate through holes in the furnace door 
for the combustion of these volatiles, resulting in large amounts 
of excess air being admitted after the larger part of tiie volatiles 
had been driven off. This practice is being discontinued for two 
reasons: (1) The excess air admitted through holes in the furnace 
door does not necessarily combine with the volatiles and effect com- 
plete combustion. Some of the air travels through the combustion 
space in streams without mixing with the volatiles. (2) After th^" 
first minute succeeding the firing of a fresh charge, the distillation 
of volatiles is considerably diminished, and all air admitted over 
the grate is in excess of the amoimt required for combustion. The 
result is the chilling of the heating surfaces, and the reduction of 
the boiler efficiency. 

At the Engineering Experiment Station, at Annapolis, Md.. 
it is now the practice to exclude all air over the grate, and to seai 
all openings in the furnace doors. When making tests, the furnace 
doors are closed as quickly as possible after a fresh charge is fired. 
It must be borne in mind, however, that the fires must be carried 
as thin as possible without allowing holes to form in the fuel bed. 

The foregoing applies particularly to the semi-bituminous coals, 
such as Pocahontas coal, usually purchased for the U. S. Naval 
Service. When bituminous coals high in volatile matter are used, 

Digitized by 


Combustion 193 

a small amount of excess air admitted over the grate may be essen- 
tial to combustion, particularly if the fuel bed forms a thick, 
pasty mass, preventing the flow of air through the fuel bed. 

Leaks in the Boiler Casing. — ^Air leaks through the boiler casing 
are extremely detrimental to boiler efficiency, and are usually 
difficult to locate. Air entering the boiler in this manner does not 
promote combustion since the gases are chilled below their ignition 
temperature by contact with the relatively cooler heating surfaces. 
Such leakage represents, therefore, a direct loss, since it takes heat 
from the hot gases of combustion and increases the smoke-pipe loss. 
The amount of air which may leak through a small opening the 
size of a pin hole is not often appreciated. 

Such leaks are best discovered by holding the flame of a lighted 
candle near the casing, when any leaks will be made apparent by 
the flickering of the flame towards the hole. These holes must be 
carefully stopped up by putty or some material which will eflfectively 
seal the opening. 


Digitized by 



Boiler Hone-power. — In engineering work, the term ''horse- 
power ^' has two meanings: (1) An absolute unit or measure of the 
rate of doing work, equal to 33,000 foot-pounds per minute ; and (2) 
an approximate measure of the size, capacity or rating of a source 
of energy. 

In the case of a boiler, the true boiler horse-power refers to the 
capacity of a boiler to evaporate water into steiun at a certain rate 
under given conditions. 

The unit of boiler horse-power adopted by the A. S. M. E. is as 
follows: 30 pounds of water evaporated into dry steam per hour 
from feed water at 100** F., and under a pressure of 70 pounds per 
square inch above atmosphere. The unit of power is equivalent 
to the development of 33,479 heat units per hour. This is also 
equal to the equivalent evaporation of 34.6 pounds of dry steam 
from and at 212** F. The term " boiler horse-power " is, therefore, 
only a measure of capacity. It is largely used as a commercial 
designation of boiler capacity and is rather loosely applied. 

Boiler Efficiency. — The efficiency of a boiler is the quotient of 
heat transmitted to the water per pound of fuel burned divided by 
the total heating value of a pound of fuel. In actual boiler tests 
the determination of boiler eflBciency is based on the weight of dry 
coal free from ash, and the amount of fuel as fired is corrected for 
this factor. The boiler efficiency (Eb), therefore, is represented 
by the equation 

^ _ heat absorbed per lb. of combustible 
*"" heating value of 1 lb. of combustible 

The term " combustible,*' in boiler tests, means coal containing no 
moisture and entirely free from ash. 

The efficiency of the boiler is the product of the heating surface 
efficiency and the furnace efficiency. The heating surface efficiency 
depends upon the shape and length of the gas passages around the 
heating surfaces and the amount of surface exposed to the action of 
Xftdiant heat. Since, by experiment, it is known that the effect of 

Digitized by 


Notes on Boiler Design 195 

radiant heat is practically constant for all rates of steaming, the 
efficiency of the heating surface is very nearly constant for all rates 
of steaming, increasing slightly at lower rates. 

It has been shown that the furnace efficiency falls off very quickly 
after a certain fixed rate of combustion has been reached, depending 
upon the size and shape of the combustion space. 

Since the boiler efficiency is the product of the heating surface 
efficiency and the furnace efficiency, the boiler efficiency falls off 
rapidly after a certain steaming rate is reached, and any further 
forcing results in an increased loss of efficiency ; this with the most 
expert firing and careful regulation of furnace conditions. 

It is evident, therefore, that poor firing, improper thickness of 
fires, and inattention to proper air supply will result in a serious 
loss of boiler efficiency, and therefore of fuel economy. Poor firing 
may result in the overall boiler efficiency being reduced from 75j< 
to 60j^, or even lower. 

Setting losses are losses caused by the leakage of cold air through 
small holes or cracks in the boiler casing. Such air entering the 
gas passages does not aid in the combustion of unbumed gases, but 
causes a loss, due to the chilling of the heating surfaces and to the 
dilution and chilling of the hot gases. The loss of efficiency from 
this source may amount to as much as 10^ if there is serious leakage. 
Such losses naturally increase with increased draft. 

Setting losses can only be reduced by a careful examination of the 
boiler casing for pin-holes and cracks, by observing the action of the 
fiame of a lighted candle. In the vicinity of a leak in the casing, 
the fiame will be drawn toward the opening. All such holes and 
cracks should be carefully stopped with some material such as fire- 
clay or powdered asbestos mixed with water. 

General Sequirements for Naval Boilers. 

Boilers for use in the naval service should be designed for high 
capacity. This means that the boiler should be capable of an equiva- 
lent evaporation of from 10 to 20 pounds of water per square foot 
of heating surface per hour. The greater the capacity, the greater 
will be the saving in weight and space. 

High efficiency is the second requirement for naval boilers, and 
a type combining high capacity willi high efficiency is desirable. 

Accessibility for cleaning and ease of repairing are important 
requisites, since boilers require frequent cleaning, and should be 
capable of being repaired by the ship's force. 

Digitized by 


196 Mabikb and Naval Boilebs 

Simplicity of oonstmction, together with a certain amount of 
flelibilitj^ is an important feature in boiler design. The multi- 
plicity of joints^ nipples and parts liable to distortion and leakage 
under steam should be avoided. The design should permit the rapid 
and easy removal of defective or injured parts, such as generating 
tubes, nipples, cross-boxes, etc. 

Oeneral DiBCussion. 

Horse-power. — When a new ship is being designed, and after her 
general characteristics have been determined, a model of the bare 
hull is constructed to dimensions and pulled through the water at 
difFerent speeds in the model basin in the Navy Yard. Washington. 
The power necessary to pull the model through the water at each 
speed is carefully ascertained, and from the data obtained an effect- 
ive horse -power curve is constructed. From this curve the effective 
horse-power necessary to drive the bare hull of the vessel at any 
desired speed can be found. The effective horse- power curve for the 
bare hull is constructed under the care of the Bureau of Construc- 
tion and Repair of the Navy. 

The effective horse-power curve is then sent to the Bureau of 
Steam Engineering, where the designs for the propulsive machinery 
and boilers are made. In this Bureau there are records of all of the 
data obtainable from the trial trips of all vessels of the Navy, and 
from those of similar vessels of other countries where such data 
could be obtained. 

The Bureau of Steam Engineering, having ascertained the maxi- 
mum effective horse-power necessary to give the vessel her maximum 
designed speed, then decides upon the type of propelling machinery 
and type of propeller to be used. 

Having decided on the type of propeller, they then look up the 
data of some vessel of similar hull and propellers and determine the 
e£Qciency of her propeller at the maximum speed of the vessel 
through the water; these efficiencies run from 50;< to 60^. From 
the propeller efficiency and other data of the similar vessel a propul- 
sive coefficient is obtained. The propulsive coefficient, at the maxi- 
mum speed, is the ratio of the effective horse-power necessary to 
pull the bare hull through the water at maximum speed to the'total 
horse-power necessary foi the engines or turbine to drive the vessel 
through the water at the same speed under the same conditions. 

Digitized by 


Notes on Boiler Design 197 

Having the total effective horee-power and the propulsive eo- 
e£Scient, the total horse-power for the engines is obtained. The 
total horse-power (H. P.) equals effective horse-power (E. H. P.) 
divided by the propulsive cod&cient. 

From the data of many trial trips of naval vessels it has been 
ascertained that the horse-power for the auxiliary machinery of a 
vessel driven by steam varies between 5^ and 6^ of the total engine 
horse-power at full power. 

The total horse-power^ when at maximum speedy of a vessel hav- 
ing reciprocating engines consists of the indicated horse-power 
(I. H. P.) of the main engines plus the I. H. P. of all of the steam- 
driven auxiliaries; that of a vessel having turbines consists of the 
shaft horse-power (S. H. P.) of the turbine plus the I. H. P. of 
the steam-driven auxiliaries. The steam for operating the evaporat- 
ing plant is not included in the above. 

The B. H. P. of a reciprocating engine is generally from 90j< to 
92^ of the I. H. P. of that engine. 

Having obtained the total engine horse-power^ it is necessary to 
design a boiler installation that will give that horse-power plus the 
horse-power for the auxiliary machinery^ and still have some reserve 

Water Kate. — ^From the records of trial trips of the latest vessels 
the water rate per horse-power of the main engines can be found. 
The water rate is the pounds of steam per horse-power per fiour. 

In the design of the boiler plant a water rate is assumed that is 
high enough^ above the actual water rate of the main engmes^ to 
give the steam for all the auxiliaries and still have a reserve. As 
an example: In designing the boilers for one of the new battle- 
ships the water rate per hour was taken as 18 pounds for the main 
eugines alone. On the trial trip the water rate was found to be 
13.38 pounds for the engines alone and 14.32 for the turbines and 
all auxiliary machinery in use on the trial. This gives 25.7^ excess 
of steam for power other than for the main engines and 20.5^ excess 
above that required for all of the steam-driven machinery in use. 

The water rate for boiler design for large boilers to be used with 
turbines or reciprocating engines is taken as 18^ which gives an 
ample allowance for all machinery on the vessel, with approximately 
20^ excess of steam. In designing small boilers, in which liquid 
fuel is to be burned, to be used with steam turbines the water rate 
is taken as 15, which gives about 10^ excess of steam. 

Digitized by 


198 Mabinb and Naval Boilbrs 

The total engine horse-power multiplied by the assumed watex 
rate gives the total number of pounds of steam required per hour. 

Heating Surface. — From boiler trials it has been found that one 
square foot of heating surface evaporates about 9 pounds of feed 
water per hour at the temperatures corresponding to the boiler 
pressures required for modem engines, without forcing. 

Orate Surface. — If the boilers are to be coal-burning, the grate 
surface is derived from the heating surface. The ratio of grate sur- 
face to heating surface equals 1 square foot to 44.5 square feet. If 
the boilers are to be liquid-fuel-burning, there must be some ratio 
between the furnace volume and the heating surface. Just what 
the best ratio is has not yet been definitely fixed. In the Yarrow 
boilers in the destroyers the ratio of furnace volume to heating sur- 
face is about 1 cubic foot to 8.6 square feet, and in the Normand 
boilers it is about 1 to 14.4. 

Tentative Flans. — The drawings of the compartments in which 
the boilers are to be installed are now obtained from the Bureau of 
Construction and Bepair, and tentative plans are made. The boilers 
are so arranged (1) that the grates of coal-burning boilers are not 
too long to be fired properly, generally not over 6^ feet to 7 feet; (2) 
that there is room between the boiler fronts and bulkheads for the 
boilers to be fired and worked properly; (3) and that no part of the 
boiler comes above the protective deck. The plans are then con- 
sidered and a type of boiler is decided upon that will give the proper 
number of square feet of heating surface with proper furnaces, and 
the best arrangement in available boiler compartment space. 

Strength Calculations. — ^The thickness of tubes, drums, headers 
and nipples for water-tube boilers are then calculated for the maxi- 
mum test pressure by the rules for thin cylinders found in any text- 
booK on machine design. If fire-tube boilers are decided upon, the 
thickness of shells, heads, combustion-chamber sheets, tubes, braces 
and stays are calculated from the general rules of machine design. 

After the arrangement and numbers of the boilers have been de- 
cided upon, tentative plans of steam and feed piping are made and 
a plan is adopted. 

Size of Piping. — ^The sizes of the main steam pipe and branches 
are then calculated, allowing a mean velocity of steam of from 
6000 feet to 7000 feet per minute. Having the pressure of the 
steam in the pipes, the density of the steam at that pressure, from 
the steam tables, and the quantity that each branch is to deliver, the 

Digitized by 


Notes on Boileb Dbsign 199 

area of the opening in a cross-section of the pipe and, theref ore, the 
diameter of tiie pipe, are easily calculated. 

The velocities in the different branches are so arranged that the 
boiler the most distant from the engines can supply its full quota 
of steam to the engine, i. e., the branches to the boilers should be so 
arranged that each boiler will supply its full quota of steam to the 
main steam line at the same pressure as any otiier one. 

Feed Piping. — ^The feed lines are calculated in the same manner, 
having the quantity of water to be delivered to each boiler, and its 
pressure ; a velocity of water in the branches to the different boilers 
is assumed from 300 feet to 400 feet per minute, from which the 
diameter of the feed main and its branches to the boilers are cal- 
culated so that each boiler will get its proper quota of water. 

The area of the openings through tiie valves in the main steam 
and feed lines is always slightly greater when the valves are wide 
open than the area of the opening through the pipes to which they 
are attached. 

The thicknesses of all pipes are calculated from the following 
formulae : 

For straight copper pipe, T= ~^ +^\ 

For steel pipe, r= (^^^^^ +,^/. 

P= pressure above the atmosphere in pounds per square inch. 
D= inside diameter of pipe in inches. 
r= thickness of pipes in inches. 

Air Supply. — ^The total area between the grate bars in the furnace 
of a coal-burning boiler must be suflBcient to pass 260 cubic feet of 
air per hour at a velocity of 30 feet per second through the fire for 
each pound of coal burned. The openings through air cones of an 
oil-burning boiler must pass into the furnace 300 cubic feet of air 
for each pound of oil burned per hour, when the air is under the 
designed maximum draft pressure. 

Oas Passages. — ^The area through the tubes of a fire-tube boiler 
or around the tubes of a water-tube boiler for the gases of combus- 
tion must equal .143 (^) times the grate area or .0032 times the 
heating surface. 

The passage through the uptakes for the passage of these gases 
must equal .143 times the area of grate or .0032 times the heating 
STurface of the boiler. 

Digitized by 


200 Marinb and Naval Boilbbs 

The passage through the smoke-pipe for the gases of combustioii 
must equal .0032 times the heating surface of all of the boilers con- 
nected to that stack. 

If there are battle bars fitted in the uptakes^ the area through them 
must equal .167 times the area of the grate or .0037 times the heat- 
ing surface of the boiler to which that uptake is connected. 

Steam Spaces. — The volume of the steam space in the shell or 
steam drum must be sufficient to allow the boiler to furnish prac- 
tically dry steam through the dry pipe to the steam drum. 

Fire-room Space. — ^When boilers are placed in double fire-rooms^ 
to allow f oy removal of tubes and handling of firing tools there must 
be at least 11' 6" clear space between the fronts of the boilers; in 
single fire-rooms there must be sufficient space between the boiler 
front and the bulkhead to permit' of the withdrawal of a tube 
through the front headers or tube sheets. 

Passages between boilers must be at least 3 feet wide. 

Itaterials. — Materials of which boilers are constructed for vessels 
in the naval service : 

Welded or fianged plates are of Class B open-hearth steel. Other 
plates are of Class A or Class B open-hearth steel. 

All rivets are open-hearth steel, Class A, or Class B, in conform- 
ity with the class of the plates that are connected by them. All 
boiler-pressure parts are constructed entirely of open-hearth steel 
plate; the tubes and headers are of seamless steel. 

No malleable or cast-iron parts are allowed in the parts under 

No screw joints are allowed in contact with the fire except in 
steam-launch boilers. 

Boiler tubes are made of cold-drawn seamless steel. The thick- 
nesses of boiler tubes are generally given in British wire-gage units 
and are as follows, depending on the outside diameter : 
4" tubes are No. 6 B. W. G.=.203'' thick. 
3" tubes are No. 6 B. W. G.=.203'' thick. 
2" tubes are No. 8 B. W, G.=.166'' thick. 

Hydraulic riveting is now required on all boiler seams, and all 
seams are caulked on both sides. Manhole and handhole plates and 
dogs are made of forged steel. 

Grate bars are made of bast iron. 

Grate-bar bearer bars are made of forged steel. 

Dead plates, door liners, lintels and door jams are made of cast 

Digitized by 



Furnace doors are made of wrought iron. 

Ash pans^ ash-pan doors and boiler casings are made of galvanized 
Glass C boiler-plate steel. 

All internal pipes in boilers are now made of steel. 

The uptake^ breeching and smoke-pipes are constructed of mate- 
rials as follows : 

Bivets^ Glass C steel-rivet rods. 

ForgingSy Class C steel. 

Shapes^ Class C steel. 

Hinges and latches^ Class G steel, cast or forged. 

Plates, Class C boiler-plate steel. 

Lagging material used is magnesia. It is covered with Russian 
iron, galvanized iron or heavy canvas. 

The materials of which the fittings and piping are made are as 
follows : 

Feed check and feed stop valves, composition. 

Valve springs, composition. 

Bottom blow-valves, composition. 

Surface blow-valves, composition. 

Boiler drain cocks, composition. 

Boiler air cocks, composition. 

Boiler gage cocks, composition. 

Boiler water gages, composition. 
Frames and fittings, composition. 
Glasses, best annealed glass with fused ends. 
Orommets, vulcanized rubber. 

Pipes less than 2" in diameter, seamless-drawn copper. 

All steam pipes V and over in diameter, seamless-drawn steel. 

Oil-fuel pipes, suction and service, seamless-drawn steel. 

Flanges for steel pipes. Class B forged steel. 

Flanges for copper pipes, composition. 

Fittings for steel steam pipes. Class B cast steel or composition. 

Fittings for copper pipes, composition. 

AU external fittings on boilers, cast steel or composition. 

Digitized by 



Formation of Coal. — Many centuries ago^ according to geologists^ 
the coal we now use was a mass of damp decaying vegetable matter. 
The mass^ had it been analyzed^ would have shown, roughly — ^water 
50^ carbon 25f(, hydrogen 3^ oxygen 20fi, nitrogen .5^ and ash 
Ij^. The decaying vegetable matter was gradually covered with mud, 
which eventually hardened into slate. From various causes, such as 
glacial movements, volcanic upheavals, contraction of the earth's 
crust, etc., this vegetable matter was subjected to high pressures and 
temperatures, and a distillation under pressure took place. During 
the distillation most of the water and volatile matter was driven ofiE. 
and the coals now mined are the result. 

The conditions under which this distillation took place in various 
parts of the world were not the same, resulting in difFerent kinds 
of coal in different localities. 

The products of the distillation vary, in different localities, all the 
way from the original peat, through the lignites, and the bituminous 
and semi-bituminous, semi-anthracite and anthracite coals, to the 
graphitic coals. 

There are, then, different varieties of coal due to the extent tc 
which the volatile gases have been driven off from the original peat 
or other woody coal-forming substances. There are also different 
qualities in each variety of coal, due to varying percentages of ash 
and water. The ash varies from 2^ to 30^, and the water from 1)1, 
in the anthracites, to 14^ in some bituminous coals, and to 2bjl or 
more in the lignites. The water is held in coals by capillary attrac- 
tion or some similar force, and the coals have to be heated to about 
260* P. to drive off. 

Peat, the first product resulting from the decay of vegetable 
matter, is the partly carbonized organic matter of bogs, swamps, 
etc. It is principally composed of moss, reeds, ferns and similar 
plants, and is found in low marshy areas. Near the surface, peat is 
brown in color and spongy; deeper down, where more decomposed, 
it is darker in color and more dense. Peat contains a large amount 
of moisture unless specially prepared. Good airTdried peat contains 
about 25^ of moisture. The heating value of peat is so low that it 
cannot be used as a fuel in marine boilers. 

Digitized by 


Coal , 203 

lignite^ or brown coal, is only slightly removed in character from 
the original vegetable matter. It retains aboat one-third of its 
original water and a large percentage of hydrocarbon gases and 
oxygen. Lignites include all the varieties of coal between peat and 
the bitmninons formations. They are usually brownish in color, 
and are high in percentage of ash. They contain a large percentage 
of water, and their heating values are much lower than those of the 
other kinds of coal. In some parts of the world lignites, compressed 
into briquettes, are used as fuel for boilers. 

Cannel coal differs from the lignites in that it contains a rela- 
tively high percentage of hydrogen. It lights readily and bums 
with a bright, steady flame. It is very compact, is dull in appear- 
ance, and does not soil the hands when handled. It differs from the 
ordinary bituminous coal in its texture. It is rich in volatile matter, 
and is used extensively in gas manufacture. 

Bituminous coal is a soft, black coal, greasy in appearance, and 
is found practically all over the world. It contains more carbon 
and disposable hydrogen, but less oxygen, than the lignites. It is 
hygroscopic in character, the amount of contained water depending 
on the relative humidity of the air and on the size of the lumps. 
Small-lump coal, having a relatively greater surface exposed to the 
air, will hold more moisture than coal of larger lumps. 

According to their behavior when being burned, bituminous coals 
are sometimes classified as coking or non-coking coals. The former 
undergo an incipient fusion, or softening, when heated, so that frag- 
ments coalesce and yield a compact coke. The latter preserve their 
form, producing a coke which is serviceable only when made from 
large pieces of coal. They are also sometimes classified as long- 
flaming and short-flaming coals. A long-fiaming coal contains a 
high percentage of volatile matter, and bums in the ordinary fur- 
nace with a long flame, due to the difficulty of supplying the volatile 
matter with a sufficient quantity of hot air to cause its complete 

Semi-bituminous coal is black in color, is harder than the vari- 
eties already mentioned, and is remarkably uniform in composition. 
It contains very little oxygen, and is low in moisture, ash, and sul- 
phur. The amount of volatiles usually varies from 17}^ to 22}i of 
the combustible matter. It is found in England, Wales and the 
eastern part of the United States. This coal ranks as the best 
steaming coal in the world. 

Digitized by 


204 Marine, AND NaVal Boilbhs 

Anthracite coal is dense black in color^ and is compact, hard and 
lustrous. Its structure is homogeneous. It does not ignite easily, 
and it bums with a feeble, smokeless flame, giving ofF intense heat. 
It is non-coking. The powdery coke made from it has no commer- 
cial value. Anthracite coal is found in England, the eastern part of 
the United States, and Colorado. 

Semi-anthracite coal has characteristics intermediate between 
those of semi-bituminous and anthracite. 

Patent Fuel. — In order to utilize the small coal or slack at the 
mines, various plans have been tried, of which the patent fuel, or 
briquette, is the only one useful for marine use. The briquette 
generally consists of fine coal with some form of binding material. 
Tar and pitch are the best binders; lime, clay or cement give too 
much ash. The fine coal and binder are mixed, baked until the 
volatiles are driven off, and then pressed into bricks. These stow 
well and have a heating value depending on the heating values of 
ihe coal and the binder. 

Oraphitic coal, found in Bhode Island, has been deprived by 
distillation of practically all of its hydrocarbon gases and oxygen ; 
it consists of fixed carbon and ash. 

Powdered Coal. — Powdered coal is coal which has been finely 
pulverized by machinery. It is forced into the furnaces through 
pipes, and is completely burned without smoke, yielding high fur- 
nace efficiency, particularly on account of the possibility of obtain- 
ing complete combustion without excess air. The use of powdered 
coal permits the use of inferior grades of coal, since the percentage 
of ash and moisture has very little effect on the combustion. Fur- 
naces may be forced to a higher rate when powdered fuel is used. 

The disadvantages are: The necessity for high-grade fire brick 
to withstand the high furnace temperature, and the danger of ex- 
plosions due to the mixture of coal dust and air. For naval pur- 
poses, the weight and space for necessary additional machinery are 
also disadvantageous. 

Powdered coal as a fuel has not been adopted in the TJ. S. naval 

Classification of Coals. — Coals are classified according to the 
relative percentages of carbon and volatile matter contained in the 
combustible portion. The following table gives the characteristics 
of the combustible portion in the different classifications, as deter- 
mined by what is known as the proximate analysis. 

Digitized by 








Bltuminoua— Eastern . 
Bituminoua— Western 

Per cent fixed I 
carbon. I 






Under 60 

Per cent vola- 
tile matter. 

3.0- 7.5 
Over 60 

Heatinpr value 

per lb. of 
in B. T. U. 

value of com- 
That of semi- 



Proximate Analysis. — There are four different factors in the 
quality of a coal that can be determined by a proximate analysis : 
(1) Moisture; (2) volatile matter; (3) carbon; (4) ash. A proxi- 
mate analysis of coal is made as follows : 

1. From a weighed sample, say a gram, of coal, the moisture 
is first driven off by heating it to a temperature of from 250® to 
300® P. for a given time. The sample is then reweighed, and the 
per cent of loss of weight is the percentage of moisture. 

2. The volatile matter is then driven off by heating the sample 
in a closed crucible to a red heat for a short time. It is then re- 
weighed and the loss is the volatile matter that has been distilled 

3. The carbon is burned out of the remaining coke by keeping it 
at a white heat with a plentiful supply of air until nothing is left 
but ash. The ash is then weighed and the difference between its 
weight and that of the coke burned is the fixed carbon. 

The heating value of a coal depends upon its percentage of total 
combustible matter and upon the heating value per pound of that 
combustible. The latter differs in different districts; it is highest 
m the semi-bituminous coals, having nearly a constant value of 
15,750 B. T. TJ. per pound of combustible. When the percentage of 
moisture and ash in any coal is known, the heating value per pound 
may be found approximately as follows : Obtain from a table (see 
following table) of data the average heating value per pound of 
combustible for the district from which the coal comes. Multiply 
this by the difference between 100^ and the sum of the percentages 
of moisture and ash. 

In selecting coal for a given type of boiler, consideration of its 
theoretical heating value alone might lead to false conclusions as to 
its suitability. The ratio of carbon to volatiles and the combustioD 
chamber space must be taken into account, as high volatile coal wiU 
not be efficient in a boiler with restricted combustion space, while it 
would be in one with ample space. 

Digitized by 


206 Marine and Naval Boilsrs 

The following table gives the heating values of various coals, 
and of various patent and liquid fuels. It also^gives the ultimate 
analysis, which is a quantitative chemical analysis; such analyses 
should be performed only by competent chemists. 

Chshical Composition or Various SrsAMiifo Coals and Liquid Fusls, thbib Hiatino 


* After sulphur and other imparities have been reinoved. 

Digitized by 


Goal 207 

Quality of a Coal. — The actual eyaporating capacity of a boiler, 
containing a given amount of heating surface and a given grate 
area, depends primarily upon the quantity of heat which may be 
generated in the furnace. This depends upon the quantity of coal 
that may be burned and upon its quality. The better the quality, 
the greater the number of heat units generated by the combustion 
of each pound. If the coal is high in moisture or in oxygen^ not 
only will the heat units derived from the combustion of it be low, 
but the attainable temperature will be lower than that from a better 
coal. If the coal is high in ash, not only is the value per ton dimin- 
ished, but the quantity of ash formed on the grate tends to check 
the air supply, to diminish the rate of combustion, and consequently 
the quantity of steam generated. If the coal is high in sulphur 
in the form of pyrites, the ash will fuse into clinker and this may 
choke the grate completely, necessitating frequent cleaning of the 

The quality of the coal is, therefore, a most important factor of 
both capacity and economy of a boiler. It is possible to obtain from 
the same boiler, with the same fireman and the same draft, twice 
as much steam when using a good free-burning coal as can be 
obtained when using poor coal. 

Ash and Clinker. — The presence of ash in coal is objectionable 
in many ways. It not only represents so much waste material, but 
also carries away a considerable quantity of unconsumed carbon 
when the fires are cleaned. This indirect waste is frequently as 
much as 50^ of the theoretical ash constituent, so that 5^ of ash 
by chemical analysis becomes 7^^ in practice. Ash clogs the fire and 
necessitates more frequent cleaning. This tends to depreciate fur- 
nace efficiency, and requires extra labor from the fireman. 

Ash not only acts as a diluent in the coal, but also retards combus- 
tion to such an extent that the boiler efficiency becomes rapidly im- 
paired. It has been shown that, with a Babcock and Wilcox boiler, 
when the percentage of ash on the grate reached 40^ of the coal, the 
useful efFect of the fire fell to zero. In other words, such a fire as 
could be maintained only sufficed to make good radiation losses. 

The composition of ash varies. Boughly, it consists of about 50^ 
silica, 30^ to 35^ alumina and oxide of iron, about 4^ to 8^ of lime, 
and a small per cent of sulphuric acid. The sulphuric acid and 
the iron oxide are derived from the iron pyrites (FeS,, sulphide of 
iron), which is often found in many coals, and is mainly respon* 

Digitized by 


208 Marikb and Naval Boilsbs 

Bible for the formation of clinker^ as the iton oxide forms a flux for 
the silica, the fusibility of which is increased by the presence of 
lime. The most refractory ash is that containing the smallest per- 
centage of lime and iron oxide. When the percentage of lime is 
about half that of the silica, a very fusible slag is produced. Al- 
though its heating value is not impaired by contact with sea water, 
salt is a bad ingredient in coal, as it increases the fusibility of the 
clinker, and the hydrochloric acid liberated in its decomposition is 
very corrosive. The mixing of coals will sometimes cause them to 
produce slag and clinker, although each separately will give a fairly 
refractory ash. This is due to ash of one coal possessing an excess 
of ingredients which provide a flux for the ash of the other. The 
incombustible elements in coal are not evenly diffused, and con- 
sequently the resulting ash or slag is unevenly distributed over the 
grate, and after a time it accumulates in places to such an extent as 
to choke the air spaces and necessitate cleaning the fires. 8ome 
slags cause deterioration of the grate bars by fluxing with the oxide 
of iron on their surfaces and eating them away. 

Coals high in sulphur generally give a very fusible ash, on account 
of the iron with which the sulphur is combined. The amount of 
ash varies greatly, ranging from 2^ to 30^, or more. It varies with 
the district in which the coal is mined, with individual mines in 
that district, with parts of the same mine, and with the care taken 
in mining it. With anthracite coals it varies with the size of the 
lumps, the larger sizes giving the least ash. 

Specification for Coal. — Semi-bituminous and bituminous coals 
are the only ones in general use in the United States Navy. 

Goal is bought for use under various specifications, generally 
written to suit the conditions under which the coal is to be used. 
Barring place of delivery and price, the most important clause under 
the latest navy specification for coal for naval vessels reads as fol- 
lows: "The coal delivered under contract must be of the best 
quality — New Siver Admiralty Smokeless run of mine coal with a 
fair proportion of lump — ^must be dry and practically free from 
slate, dirt, sulphur and other impurities and subject to the usual 
inspection and test. Goal to be inspected for quality and quantity 
at point of shipment 

Eenfs " Steam Boiler Economy '^ gives a definition of the stand- 
ard coal as follows : 

" The standard coal is a semi-bituminous coal containing not over 

Digitized by 


Coal 209 

20;^ of volatile matter, 2^ of moisture and 6^ of ash^ the remainder 
being fized carbon^ the determinations being made by proximate 

A very good specification for buying coal would be as follows: 
Coal to have not over .S^ of sulphur. A reduction of 1^ in the 
price to be made for each 1}1 of volatile matter in excess of 25^; 
also a reduction of 2^ for each Ijt of ash^ and 2ji for each Ijt of 
moisture in excess of the standard. 

Effect of Moisture in Coal. — The presence of moisture in coal is 
objectionable because it has to be converted into steam and re- 
jected at the temperature of the smoke-pipe gases^ and the heat 
required to do this is lost. Under the ordinary conditions the mois- 
ture varies from Ijt to 5^, though small coals will sometimes hold 
much more. The approximate heat loss will vary from 12 to 144 
B. T. U. per pound of coal, according to its condition. 

Effect of Weathering on Coals. — On being exposed to the weather 
the quantity of oxygen and indisposable hydrogen in coal, and the 
weight of the coal, will increase. The quantity of carbon and dis- 
posable hydrogen will diminish. There will be a reduction in the 
calorific value of the coal. 

On an actual test three coals held at a temperature of 158^ to 
180® P. for 14 days lost on an average of 3.6^ of their calorific value. 
If coal be piled in the open, and there is no rise in its temperature, 
it will not suffer any sensible change in calorific value. If there be 
a rise of the temperature, it loses carbon and disposable hydrogen 
by oxidation ; it increases in absolute weight, on account of the in- 
crease in oxygen and indisposable hydrogen; there is no change in 
the amount of sulphur; and there is a loss in the total calorific value 
of the coal. 

An excess of pyrites in coal tends to produce rapid oxidation and 
mechanical disintegration of the mass, with the development of 
heat, loss of coking power and spontaneous ignition. In coking 
coals, weathering reduces and finally destroys the coking power, 
while the pyrites are converted from the state of the bisulphide into 
the comparatively innocuous sulphates. 

Storage of Coal XTnder Water. — Experiments have been con- 
ducted in the last few years with a view to determining the effect 
on coal of storage under salt water. These experiments lead to the 
conclusion that underwater storage prevents the reduction of 
calorific value occurring with weathered coals and prevents spon- 
taneous combustion. 

Digitized by 


210 Mabinb and Nayal Boilers 

Stowage* on Board Hen-of-War. — Coal is stowed in bunkers. 
There are generally two tiers of them. The lower tier extends 
vertically from the inner skin of the ship to the protective deck, and 
is ranged alongside of the fire-rooms and engine-rooms, and some- 
times athwartship between the after fire-rooms and forward engine- 
rooms and between the forward fire-room and forward part of the 
ship. Those forward and abaft the fire-rooms conmiunicate with 
those abreast the fire-rooms, and those abreast of the fire-rooms com- 
municate with the fire-rooms by means of water-tight doors. Those 
in the upper tier are between the protective deck and the second 
deck, and extend from the ammunition passages to the side of the 
ship. They communicate with the bunkers of the lower tier by 
water-tight doors leading into the lower bunker-filling chutes, and 
in the latest ships they have chutes leading directly to the fire- 
rooms; they generally conmiimicate with other upper bunkers 
through water-tight doors. 

All bunkers are filled through filling chutes leading from the 
upper, main or second decks. They have ventilating pipes leading 
from the highest point in them to the atmosphere. This is for 
ventilating the bunkers and for carrying away any gases that may 
be given off by the coal. 

Chutes for filling the lower bunkers are placed as nearly as pos- 
sible directly over the doors leading into the fire-rooms. The upper 
bunkers have doors opening into these chutes for trimming the coal 
from them into the lower bimkers. 

All bunkers have escape plates, which can be opened from the 
bunker, for the exit of any one caught in the bunker. They should 
be located as near as possible to the entrance of the filling chute, 
in order that, when the bunker is nearly full, the last man to leave 
the bunker may remain as long as there is room for him to work, and 
then enter the escape and work the coal down as it runs from the 
chute until the bunker is entirely full. If the escape is not located 
near the filling chute, space is always left in the bunker from the 
chute to the escape. 

For the same reason, large bunkers have more than one filling 
chute. This prevents extra handling of the coal in stowing the 
bunkers. They also have trolley rails and trolleys for carrying the 
coal buckets to the fire-room doors. 

* " Stowage " Is the term for arrangements for placing and keeping 
coal on board. 
" Storage " is the term for accumulating for use. 

Digitized by 


Goal 211 

All swinging doors to bunkers open away from the bnnker, except 
those doors to bunkers distant from the fire-rooms; they open into 
the bunkers nearer the fire-rooms. All bunker doors opening into 
the fire-room are vertical sliding doors. 

All bunkers have automatic fire alarms that ring a bell when the 
temperature is above that for which they are set — ^usually 212** F. 
The bells indicate on an indicator suitably located. 

Some bunkers have means for blowing steam into them for ex- 
tinguishing any fire that may start in their coal. 

Goal must not be taken on board wet if it can be avoided, and care 
must be taken to keep it dry in the bunkers, as moisture sometimes 
causes a rapid and dangerous generation of heat and gas, resulting 
in spontaneous combustion. Before the decks are washed down 
after coaling, the solid bunker plates must be replaced and made 
tight to prevent water from getting into the bunkers. Should there 
be any indication of spontaneous combustion, it must at once be 
reported to the officer of the deck and to the executive and com- 
manding ofScers. 

The ventilation pipes fitted to the bomkers must be kept clear, 
and they must always be kept open for ventilation, except when 
running the blowers and when a loss of air pressure in the fire- 
rooms through open bunkers would be caused thereby. The plates 
of all fixed coaling trunks and coal bunkers not provided with 
permanent ventilation fittings must be taken oflf periodically to ven- ^ 
tilate these spaces. This must be done at frequent intervals after 
coaling, as the evolution of gas owing to the breaking up of the 
coal is very rapid during, and for some days after, the operation of 
coaling ship. It must be borne in mind that to secure efficient 
ventilation there must be at least two openings, one for the admis- 
sion of pure air and another for the escape of foul air; and, where 
permanent ventilation fittings do not include both, the bunker 
plates must be taken off periodically as required above. Care must 
be taken to ventilate such bunkers thoroughly before any men are 
sent to work in them. 

No open light must be permitted in a coal bunker, or within 20 
feet of an opening into a coal bunker, until the bunker has been 
thoroughly ventilated and it has been ascertained, by a safety-lamp 
or other suitable means, that it does not contain explosive gas. 
Special precautions in this respect must be taken for a few days 
after coaling. In any case in which the distance of 20 feet is im- 
practicable, the distance kept must be as great as possible. 

Digitized by 


£12 Marine and Nayal Boilers 

Daring the intervals between steaming periods, and at other 
times when it may be done to advantage, the coal must be trimmed 
from the upper and more remote bunkers into close proximity to 
the bunker doors of the fire-rooms where it will eventually be re- 
quired for use. This is specially important as preparatory to steam- 
ing at a high rate of speed, when a considerable supply of coal will 
be needed. The engineer oflScer must keep himself informed of the 
general distribution of coal in the bunkers. 

Coal must not be stowed in the fire-rooms in such quantities as 
to interfere with working the boilers, or to cover up the handles or 
wheels of valves, or to get into the bilges, thereby possibly choking 
the pump suctions and strainers and endangering the safety of the 

Precautions Taken in Determination of Amount of Coal Beceived. 
— Inspection of Cargo. — The commanding officer of the first ship 
to coal from any chartered collier will cause inspection to be made 
of batches to cargo holds, with the view of ascertaining if the cargo 
of coal is intact and has not been broached by the collier herself. 

Inspection of Winches and Gear. — Commanding officers will have, 
in company with the master of the collier or officer detailed by him, 
an inspection made of deck winches and other appliances belonging 
to the collier, both before and after coaling, in order to avoid any 
dispute as to claims for damages of the collier's gear. Ordinary 
wear and tear not included. 

The draft of the collier and of the ship coaling, forward, amid- 
ships, and aft, will be accurately taken before and after coaling. 

Loss Overboard. — Sufficient screens will be spread between the 
ship and the collier to avoid loss of coal overboard by drag of bags 
along the collier's decks and rails. Screens will also be provided to 
prevent the loss of empty bags while being returned from ship to 
collier. Not over 1^ loss is allowed for coal in handling from collier 
to ship. 

A sufficient number of tallymen will be furnished each collier, by 
the ship coaling, to assist the master of the collier to tally bags as 
they come out of the holds. The ship coaling will have sufficient 
men stationed to tally accurately the number of bags hoisted on 
board. To determine the weight of a bag there will be detailed a 
weighing party under the charge of an officer. This party will be 
provided with accurate scales, and bags will be weighed continuaDy 
during the coaling. The scales will be moved from time to time. 

Digitized by 


Coal 213 

80 that coal coining from all the hatches of the collier may be 
weighed. The average net weight of all the bags weighed will be the 
established weight of a bag of coal for that coaling. The average 
weight of empty bags will be accurately determined during every 

In calculating bunker capacities, the fonner practice was to as- 
sume the density of the coal to be 43 cubic feet to the ton, and to 
assume bunkers stowable only to within 6 inches of the lower edge of 
the deck beams. In some cases the capacities of the permanent 
chutes were included ; in other cases they were not. 

The present standard practice is to assume the bunkers stowable 
to the lower edge of the deck beams, and on this assumption the 
capacity of the blinker is calculated for several different densities 
of coal, ranging usually from 41 to 44 cubic feet to the ton. Per- 
manent chutes are now included in all calculations. 

Tables of bunker capacities, calculated as described above, are 
furnished each new ship. Since the advent of the engineering com- 
petition, the bunkers of most of the principal ships, which were 
originally calculated at 43 cubic feet and to within 6 inches of the 
deck beams, have been recalculated in accordance with present 
standard practice, and tabular statements of results have been fur- 
nished the ships. 

In vessels in which bunkers were measured according to the 
original practice and have not been recalculated in accordance with 
the prevailing practice, the bunkers should be recalculated by the 
engineer ofScer. As it is found practicable to stow most bunkers to 
the lower edge of the beams ; and as the actual weight of coal in a 
bunker will vary considerably with varying densities of coal, bunker 
estimates will be unreliable unless this recalculation is effected and 
a table is prepared, showing the capacity of each bunker for each 
different density, and the density of the coal is accurately deter- 
mined while coaling is going on. 

During the coaling, the density of the coal will be determined 
by the officer in charge of weights, weighing at least once each hour 
a known number of cubic feet of coal. The receptacle used for this 
purpose shall' contain not less than 16 cubic feet, and its capacity 
will be ascertained with the utmost accuracy. The density ascer- 
tained by the average of these hourly weighings will be the argument 
used in entering the aforementioned table, and the bunkers will be 
estimated in accordance with the stowage of bunkers and trunks. 

Digitized by 


214 Mabinb and Natal Boilers 

which latter shall be ascertained by the senior engineer officer in 

At the inspection before coaling begins, great care must be exer- 
cised in estimating the coal remaining in partially filled bimkers 
that are to receive more coal> and in converting the estimate into 
terms of cubic feet to be used in connection with the estimate of 
coal received in such bunkers during coaling. Coal used between 
the times of the first and second estimate must also be taken into 

When coal is received from a source other than a chartered collier, 
the above regulations will be observed as far as they are applicable. 

While a vessel is coaling, an hourly report of the amount of coal 
taken on board during the past hour will be made by signal to the 
division commander or senior officer present. If a ship has not been 
coaling during the entire hour^ a time signal will be made with the 
amount taken on board. All such signals will be recorded by the 
ship sending them and by the ship receiving them. When the coal- 
ing is completed^ signals will be made reporting that f act, together 
with the total taken on board during that coaling. 

When a hold has been emptied, it will be swept clean of coal and 
the collier's deck also will be swept. 

Receipt for Coal Received. — Immediately upon the completion of 
coaling from any collier, the commanding officer will give a written 
receipt to the master of the collier for the tons of coal received, and 
will send direct to the fleet flagship a duplicate of the written 

When a collier is completely discharged by a vessel of the fleet, 
the commanding officer will report immediately the date, hour and 
minute of such completion of discharge, not only by written report 
but also by signal. 

Coaling Ship. — Coal is purchased from the coal dealers on yearly 
contracts under the Navy Department Specifications. It is analyzed 
and tested at the Navy Yard, Washington, D. C. It is delivered to 
colliers or coal barges from cars. The amount of coal delivered to 
the collier or barge is determined by weighing the car in the pres- 
ence of a government inspector before and after the co&l is dumped. 

The collier or barge is brought alongside of the ship to be coaled, 
and the coal is whipped up to the deck of the ship in coal bags of 
about 600 pounds capacity. This is done by means of the coaling 
machinery of the ship and collier, or, in case of a barge, by that of 

Digitized by 


Goal 216 

the ship. Each bag is tallied as it comes on board by men of the 
ship^s force stationed for that purpose^ and about one bag in every 
ten is weighed, the average weight of coal per bag being calculated 
from the average of the total number weighed. 

When brought alongside in a collier, the draft of the collier for- 
ward and aft is taken before and after coaling. 

From the tons-per-inch curve of the collier a check may be made 
on the amount of coal received. Allowance must be made for any 
other weights received upon or discharged from the collier during 
the coaling. 

The same measurements should be made on the coaling vessel, 
both before and after coaling; the amount, corrected as for the 
collier from the tons-per-inch curve of the coaling vessel, should 
agree with that from the collier. 

Goal is whipped out of the hold of the collier by her own winches 
and booms and landed on the deck of the coaling vessel, tallied and 
weighed in the same manner as described above. 

The bags are then taken to the bunker-filling chutes on trucks, 
and the coal is dumped down them. The details for filling the bags 
on the collier or barge, for running winches, for tending all gear on 
deck, and for weighing and trucking the coal to the bunkers and 
dumping it into the filling chutes, are from the gun divisions of the 
ship and the marines. After the coal is placed in the filling chutes, 
it is handled by men from the engineer's force. When the ship is 
built, the bunkers are carefully measured up to within 6" of the 
lower edges ^of the overhead beams, and the capacity of the bunkers 
is calculated at the rate of 43 cubic feet of space per ton of coal. 

Plans of the bunkers with these capacities are furnished the vessel 
with her outfit of plans, when she is first commissioned. 

When the coal is poured into the bunkers, the engineer's force 
trim it away from the chute, filling the bunker to its utmost capac- 
ity. They keep the chute clear while the bunker is filled around 
them, until they cannot work longer to any advantage. After the 
bunker is filled so much that the last man can stow no more coal, 
he leaves the bunker either through the escape plate or the filling 

After the coal trimmer is out of the bunker, coal is dumped into 
the chute as long as it will run from the chute into the bunker. 
If the chute is a permanent fixture, it is also filled. The bunker is 
now considered to be full and is closed up. It is then assumed that 

Digitized by 


216 Mabinb and Nayal Boilebs 

the bunker contains the amount of coal called for by tlie original 
bunker measurements. When each bunker is reported full, it is in- 
spected ; if it is not filled, the coal is worked back from the escape 
and more coal is added until it is full. 

Before coaling is begun, the coal in all unfilled bunkers must be 
estimated carefully and the total amount on hand be ascertained. 
After coaling is finished, the estimate should be made again and the 
total amount taken on board be ascertained. If the estimates are 
carefully made, the amount found should agree, within 20 tons, 
with the corrected amount taken from the tons-per-inch curves of 
the ship and collier. 

It is well to have a standard box on board ship, the cubic capacity 
of which, level with the top, is known accurately. While coaling 
is progressing, weigh this box, level full, get an average of ten 
weights, and calculate the number of cubic feet of space required per 
ton of the coal. 

Becords of Coal Consumption. — ^After coaling, the average net 
weight of ten buckets of coal taken from the bunkers is obtained 
and recorded. 

As the coal is removed from the bunkers for use, each bucket 
is tallied, and at the end of each hour the water tender on watch 
gives to the machinist in charge of the steam log the number of 
buckets of coal used for each purpose. This machinist enters in 
the log, in the proper column, the number of buckets used. The 
log writer takes the record of the number of buckets per hour and, 
using the average weight, calculates the number of tons of coal 
used per day for each purpose and the total amount used for aU 
purposes. He enters the amounts in tons and decimals (one place) 
in the proper columns for these entries on the smooth log sheets. 
This record is kept from midnight to midnight 

A second record is kept, similar to the above, for total expendi- 
tures of coal from noon to noon. The amount on hand at noon and 
the amount expended are signalled to the commander-in-chief oi 
the senior officer present at noon of each day. 

This record is checked by frequent inspections of all bunkers 
from which coal has been taken, and estimates are made of the coal 
in all such bunkers. The total amount on hand is determined in 
this way, and if the record has been kept correctly, the amount on 
hand by coal account and by estimate should agree. If it is found 
that they differ by 20 tons or more, the coal account should be 

Digitized by 


Coal 217 

bronght to show the amount on hand by an " expenditure or re- 
ceipt by inspection '' of the difference. 

Coaling at Sea. — A method of coaling ship at sea has just been 
successfully tried out with the collier towing a battleship. The 
method consists of a trolley wire extending from a coaling boom 
on board of the collier to a boom or mast on the forecastle of the 
ship. This wire is kept properly taut by appropriate towing engines 
or winches. The coal in bags is whipped up to the trolley and sent 
over it to the ship, where it is lowered to the main deck and stowed 
in bunkers in the usual way. This method, devised by Ligerwood 
and Miller, has conformed to the contract requirements of deliver- 
ing to a battleship coal at the rate of 60 tons per hour for six hours. 

Storage of Coal and Spontaneous Combustion. — It has been 
f oxmd by experiment that all coals, except anthracite, when stored 
in the same way eventually ignite from spontaneous combustion, if 
the pile is over a certain definite number of feet (20) in height. 

The length of time elapsing between that of the storage and that 
of the spontaneous ignition varies with the qualities of the coals. 
Those high in moisture and iron pyrites ignite first, and those of 
high volatile composition, containing much oxygen and moisture, 
come next. Coals of the above compositions heat in or near the 
center of the pile and give off gases. The rise in temperature and 
the smell of gas are the early indications of spontaneous combustion. 

The most usual causes of local external heating are those due to 
heat from a boiler or steam pipe communicated to a coal bunker. 
If the bulkhead of a bunker containing coal with a tendency to 
absorb oxygen is kept at 120® F., there is a great chance of spon- 
taneous ignition in a few days. Ignition may take place near the 
center of the bunker and with sufficient radiation would result in 
simply charring the coal. Waste, oily with fatty oils easily oxi- 
dized, may start a fire spontaneously, but mineral oil is said to 
retard heating. 

Defective ventilation is that which renews air sufficiently to sup- 
port combustion faster than it removes the heat to reduce the tem- 
perature below the point of ignition. 

Coal should contain as large a percentage of lump and as little 
slack as possible, as in the latter resides the primary causes of 
spontaneous ignition. It should not have a high percentage of 
combustible volatile matter. 

Digitized by 


218 Mabinb and Nayal Boilers 

Coal should be at least a month from the mines^ because it 
evolves marsh gas and absorbs oxygen more readily when it is newly 

It should not be loaded or stored- in a wet or damp condition. 
The maximum percentage of moisture should be 3^ and that only 
when the coal is to be unloaded and used in the near future. 

Ventilation is ordinarily effective on naval vessels^ on account 
of the comparatively small amount of coal in the bunkers and the 
access at top and bottom. In colliers, however^ perfect ventilation 
is impossible, on account of the amount of coal in the cargo spaces; 
and the cargo hatches should be battened down to exclude the fresh 
supply of air. Hatch covers, however, should be removed at times 
when the external air is cooler than the surface of the coal which 
shows signs of heating. 

Thermostats are installed on naval vessels, to give warning of 
increase of temperature in bunkers; and in colliers, pipes plugged 
at the lower end should be driven into the hold for the purpose 
of dropping thermometers therein to get the temperature of the 
interior of the pipe. 

When coal is heating, it gives out a characteristic and penetrating 
odor. The gases evolved consist of nitrogen, water vapor, carbon 
dioxide, carbon monoxide, hydrocarbons of a parafiin series, and 
sulphuretted hydrogen. 

In a poorly ventilated bunker, in which spontaneous combustion 
is started, the gases, carbon monoxide and marsh gas, rise to the top 
of the bunker. By the time they reach the top of the coal they are 
cooled off and remain in the space above the coal. When mixed 
with the proper proportion of air, the result is a highly explosive 
mixture which a flame will set off. 

Neither of these gases supports life, and carbon monoxide is 
poisonous. For the above reasons, before entering bunkers, they 
should be investigated for a smell of gas. If the smell of gas is 
noticeable, the bunker should be well ventilated before anyone is 
allowed to enter it. After ventilation, the bunker should be tested 
with a safety-lamp. The presence of gas in the bunker will be 
indicated by a blue cap on tiie yellow flame of the safety lamp, and 
the height of the blue increases with the percentage of gas present. 
An experimental safety-lamp is^now being tried which has a brass 
bonnet surrounding the gauze. The bonnet renders the lamp safe 
under all conditions in explosive mixtures of gas, but it reduces the 

Digitized by 


Coal 219 

height of the blue cap (the danger signal) of the flame. An indica- 
tion of the percentage of gas in the bunker can be obtained with 
the bonnet of the lamp off, but the lamp must be handled by a care- 
ful man; dropping it or tilting it so the flame strikes one portion 
of the gauze, for any length of time, may cause an explosion. The 
following safety precautions are suggested: 

1. Test upper portions of a bunker for gas : (a) when the bunker 
has been closed for longer than 60 hours; (b) when the bunker has 
been closed for 12 hours, if the coal is Welsh coal or any coal other 
than that ordinarily used. 

2. If there be indication of gas, ventilate well, using fans if neces- 
sary; then retest for gas. 

3. These tests should be made by a reliable man not below the 
grade of chief water tender. 

4. Glean and inspect safety-lamps after use; a hole in the gauze 
makes the lamp unsafe. 

5. Use only lard or sperm oil in the safety-lamps. Kerosene 
deposits soot on the gauze, and the deposit may glow enough to 
ignite the fire damp. 

Digitized by 




The term liquid fuel may be applied to all compounds of carbon 
and hydrogen which are fluid at ordinary temperatures^ or which 
may be readily rendered fluid by the application of heat. The vege- 
table and animal fats and oils are not obtainable in sufficient quan* 
tities to supply the other demands upon them^ and are not in use 
as fuels. The liquid fuels in use for boilers are as follows : 

1. Mineral hydrocarbons^ the chief of which is petroleum. 

2. Shale oil, produced by the distillation of the bituminous shales. 

3. Tar oil, a by-product in the process of the distillation of coal 

4. Blast-furnace oil, a similar product from blast furnaces. 

The oils of the second, third and fourth classiflcations are scarce, 
and are used only in the vicinity where made. 

Mineral hydrocarbons, the petroleums, are the only liquid fuels 
produced in sufficient quantity to be considered as a fuel for marine 
boilers. Oil fuel has superseded coal to some extent in the mer- 
chant marine and to a large extent in torpedo-boat destroyers, and 
is displacing coal on large men-of-war. The extent to which oil 
will continue to supersede coal will depend upon the somewhat 
doubtful continuance of its production in sufficient quantities. 

The Supply of Oil Fuel. — The principal oil fields of the world 
are: The United States, Bussia, Oalicia, the Dutch East Indies, 
Roumania, India, Mexico, Japan, Peru, Germany, Canada and 
Italy. The principal fields in the United States are : Pennsylvania, 
Ohio, Indiana, California, Texas, Oklahoma, and Kansas. 

Classes of Oils. — From the standpoint of fuel oil, there are two 
classes of petroleum as it comes from the well: (1) One that boils 
down, after successive distillations, to paraffine; (2) one that boils 
down, after successive distillations, to thick, heavy asphdltum. 

The petroleums found in the Appalachian mountain system, in 
Ohio, and in Indiana, belong to the paraffine series; while those from 
Texas and California belong to the asphaltum series. 

Digitized by 


Liquid Fuel 221 

Properties of Fetrolenm. 

Petroleum, as obtained from the earthy is a dark fluid, and is 
accompanied by hydrocarbon gases, water and earthy matter. The 
earthy matter is mostly salt and sand. This is crude oil. 

Crude oil contains many series of the hydrocarbons, from those 
of boiling points lower than the temperatures of the atmosphere to 
those of high boiling points. The two principal hydrocarbon series 
in the petroleums are the paraffines and the ole fines the first having 
the general formula C«H2«+2> which begins with 7i = l, giving CH^ 
(marsh gas) ; and the second having the general formula GnB.2n9 
which begins with n=2, giving CgH^ (olefiant.gas). There are 
other series called the naphthenes, henzines, etc. 

When crude oil is drawn from the earth, the gaseous hydrocarbons 
having a boiling point lower than the temperature of the atmos- 
phere are given off. These gases are caught and distributed for 
light and power purposes in the vicinity of the wells. 

After the crude oil is drawn off, it is allowed to settle, and the 
vrater and earthy matter are removed. 

The members of the hydrocarbon series are gaseous for low values 
of n. In the paraffine series they are gaseous below n=5; are 
liquids for values of n= 5 to 26, inclusive; and are solids when 
n=27 and above. 

The boiling points increase in an arithmetical progression as n 
increases, the difference being about 20^ G. or 68^ F. for each step 
in the series. 

Fractional Distillation. — After the water and earthy impurities 
are removed, the oil is sometimes subjected to what is called frac- 
tional distillation. The oil is placed in a still, and the temperature 
is raised to a certain fixed point. All of the hydrocarbons of lower 
boiling point are distilled off and caught in a condenser. The 
temperature of the still is then raised to a higher point and the 
distillate is caught. This method is continued until all of the more 
valuable distillates obtainable from that particular oil are distilled 
off and the residue is disposed of as liquid fuel. 

The remaining oil and the distillates consist of many members 
of these hydrocarbon series chemically combined. In the Bussian 
oils, the naphthenes predominate; in the Pennsylvania oils the 
paraffines; and in the Texas and California oils the asphaltums. 

Fuel oil is the refuse of crude petroleum after the more volatile 
products have been distilled off, or it is the crude oil from the weU 

Digitized by 


Mabinb and Natal Boilers 

after the water and sediment have settled, if the flash point is 
BufSciently high to make it safe. The percentages of fuel oil left 
after the more volatile products are given off are in percentage by 
weight as follows : 

Fuel-oil residue from Pennsylvania and Ohio oils 6 to 10 

Fuel-oil residue from East Indian oils 60 to 70 

Fuel-oil residue from Texas and California oils 60 to 80 

Fuel-oil residue from Russian oils 50 to 60 

Some crude petroleums do not yield enough of the more valuable 
products to pay for refining, and, having a flash point sufficiently 
high for use as fuel oils, are sold as such directly from the settling 

It can be seen from an examination of the hydrocarbon series that 
the proportion of carbon to hydrogen is practically constant, and 
independent of the value of n. This explains why there is very 
little difference in the calorific value of various fuel oils. Such 
differences as are found to exist are generally due to the presence 
of small percentages of oxygen, nitrogen and mineral impurities 
of no calorific value. 

The fractional distillates generally comprise oils as follows : 

1. Light oils or petroleum spirit, gasolene, etc. 

2. Illuminating oils, kerosene. 

3. Lubricating oils, light and heavy. 
• 4. The residue known as fuel oil. 

In some crude oils it does not pay to carry the distillations to 
this extent. It may be carried past the first, second or third stage, 
depending upon the characteristics of the crude oil. The Pennsyl- 
vania oils are carried through the three stages, and leave only a small 
residue. The Texas and California oils are generally carried 
through the second stage, and leave a large residue. Russian crude 
is not distilled. It is stored in open reservoirs until it has lost its 
most volatile constituents. It is called mazut Naphtha is a term 
applied to Russian fuel oil. It is the residue after tiie illuminating 
oils have been distilled off. 

Fuel oils usually contain about 1^ of moisture and from 1.6}i to 
4j< of nitrogen, oxygen and sulphur. Some oils contain more sul- 
phur than others. 

Digitized by 


Liquid Fuel 


Analyses. — ^The following are the analyses of the more promi- 
nent oils : 

Texas Beau- 

mont crude. 







sian light 

sian heavy 






• refuse. 



field oil. 














































Physical Characteristics of Fuel Oil. 

Color. — Fuel oils vary in color from greenish through brown to 
black. Very light brown or light green indicates a light oil, full of 
gas; this color is characteristic of light, unrefined oils and low- 
boiling distillates from paraflBne-base oils. Heavy black oils are of 
asphaltum base. 

Specific Gravity. — Their specific gravity varies from 1.026 to 
.749, that of water being taken as unity; and it is generally stated 
in terms of the Baum6 scale.* The specific gravity at 60** P. can 
always be obtained from the Baumfi degrees by the following 
formulae : 

When greater than unity: 
When less than imity: 

Specific gravity — 
Specific gravity = 



130 + deg. B. 

The specific gravity is a most important standard in classifying 
oils. Oils are rated in gravity in Baum6 degrees at a temperature 
of 60** P. Heating the oils lightens them from 2** to S** Baum6 
for every 100** P. rise in temperature. 

The market fuel oil ranges from 10** to 30** Baum6. 

* The density or specific gravity of oil is measured by the 6aum6 hy- 
drometer. This instrument is graduated in degrees to accord with the 
density of a solution of common salt in water as follows: For liquids 
heavier than water, the zero of the scale is obtained by immersing in 
pure water; the 5*" mark, by immersing in water with 5% of salt; the 
10^ mark, in a 10% solution, etc. For liquids lighter than water, the 
zero mark is obtained by immersing in a 10% solution of brine; the 10* 
mark, by immersing in pure water. After obtaining the length of a 
degree for liquids heavier and lighter than water, the stem of the 
hydrometer is graduated by measurement , 


Digitized by 


224 Mabike and Naval Boilers 

A formula in which the specific gravity in degrees Bailing is a 
factor was published by A. C. Sherman and A. H. KnopflE, in 
the American Chemical Society, in October, 1908, gives the calorific 
value of the American petroleum oils. Formula: B. T. TJ.= 
18,650 + 40 ( degrees Baum6 — 10 ) . This formula gives the approxi- 
mate calorific power in terms t)f the specific gravity. 

A table of the calorific values of some of the fuel oils foimd by 
this formula and checked by calorimetric determinations is given as 
follows : 

B. T. u. B. T. u. 

calorimeter calculated from 
"^ determination. formula. 

Pennsylvania fuel oil 19,656 19,526 

Kansas crude 19,389 19,578 

Texas crude 19,242 19,332 

Indian Territory 19,418 19,342 

California crude 18,779 19,150 

California refined 19,555 19,530 

In S9}i of the determinations made in the above way, the calcu- 
lated values were within l}i of those found by calorimetric deter- 

The specific heat of liquid fuels is about .511. Their latent 
heats of evaporation are variable, averaging about one-ninth that of 
water, say 107.3 B. T. U. ' 

Odor. — ^The fuels from particular districts and from certain re- 
fineries can be located by their odor after some experiences with the 
diflferent ones. Sulphur gives to the fuel in which it is contained a 
characteristic odor very perceptible when the percentage is above 1. 

Viscosity. — The viscosity of an oil is the rate of flow, of a cer- 
tain amount, through a specific orifice at a certain temperature. 
The vessel in which the oil is placed is called the viscosimeter. In 
the U. S. Navy, the Engler viscosimeter is the standard. 240 e. c. 
of oil are placed in the cup, the temperature measured and 200 c. c. 
are allowed to run out. The time is noted, and comparison is made 
with water at 70° F. 

,7. .. . . , T time of flow of oil 

Viscosity at temperature used = -: 7-7.- ^ — - . 

-^ ^ time of now of water 

Digitized by 


Liquid Fubl 225 

Viscosity falls much more rapidly with rise in temperature than 
does gravity. 

The viscosity of fuel oils is an indication of the ease with which 
they will flow or be pumped; the nearer their viscosity to that of 
water, the greater the ease with which they can be handled. 

Oils of 20** Baum6, 16 viscosity, flow rapidly with a slight head; 
those of 18®, or 75 viscosity, can be piped readily, but oils heavier 
than this and of higher viscosity require a good pressure, or heating, 
or both. 

The viscosity of oil is the main point to consider in its proper 
burhing. In order to have goo<l atomization and smokeless com- 
bustion the viscosity of the oil must not be above 8 Engler, and if 
above 8 Engler must be reduced by heating. The use of additional 
heat to further lower the viscosity below 8 Engler in no way im- 
proves the evaporization. Heating an oil also aids in dissociating 
any water that may be in it. The capacity of a burner is increased 
by heating the oil up to a point called the critical ; after this point 
is reached, additional heat lowers the capacity. This is shown in 
the temperature capacity curve of a burner, operating at a constant 
pressure, the temperature of the oil being changed, Plate XVIII. 

The plate of Temperature- Viscosity curves shows the temperature- 
viscosity curves covering most of the oils in use for fuel. 

Flash Point. — The temperature at which oils give oflE suflBcient 
vapor to flash on the application of a flame or spark is called the 
flash point of the oil. It is determined in the United States naval 
service with the Pensky-Martens closed-cup testing apparatus. The 
flash point of a fuel oil is an important indication of the fuel as a 
carrier of lighter and low-boiling-point constituents. 

A knowledge of the flash point of any liquid fuel is essential to 
the consideration of its suitability for use on board ship, and espe- 
cially so for use on naval vessels. Fuels of a high flash point are 
safer than those of a low flash point. 

For the tests of the flash points of different fuels to be of com- 
parative value, they must be made in exactly the same manner. 
They must be tested with the same apparatus, at the same rate of 
heating, and the flame must be applied in exactly the same way. 

The United States Naval Liquid Fuel Board, which conducted 
exhaustive experiments in 1904 and was responsible for most of 
the pioneer work in oil-burning in the United States, recommended 

Digitized by 


226 Marinb and Naval Boilebs 

that no oil of lower flash point than 175^ F. be used in the TJ. S. 
Navy. More recent experiments and increasing demand for oil have 
led to the adoption of a minimum flash point of 150^ F. The mini- 
mum flash points in the several navies of the world vary from 
150® F. to 248® F., while in the merchant service oils are used with 
flash points as low as 75® F. 

Fire Point. — If a fuel oil is heated higher than the flash point, it 
will arrive at a temperature at which, if a flame or spark is applied 
to the gases, they will burn steadily. This temperature is called the 
fire point. It is generally less than 50® F. higher than the flash 
point, and is usually about 26® F. above it. 

Notes on Storage and Transportation of Liquid Fuels. 

The lighter petroleums have very pronounced searching qualities 
and their fumes have great penetrating power. A joint that is 
tight under a certain water pressure may show oil leaks at that 

Oils of lower gravity, Baunie, and higher flash point will be less 
likely to leak, and less fumes are given off. If a joint is tight, with 
water under a certain pressure or head, it will be tight with the 
heavier oils at the same pressure. 

The gases from liquid fuel oils arp comparatively heavy and re- 
main near the oil surface, or near the bottom of the tank when the 
tank is empty. They can be entirely freed from an empty tank only 
by flUing it with water and washing it out imtil the tank is entirely 
free from gas. 

With oil having as high a flash point as 200® F., vapors will form 
to a slight extent, but not in suiBeient quantities to be dangerous 
if the tanks are tight and are properly ventilated. The nature of 
the ventilation depends upon the nature of the storage. 

The specific gravities of oil and water being very nearly the same, 
the oil does not rise to the top and free itself of water very readily, 
unless it is heated. When heated, its specific heat is much less than 
that of water ; therefore, it heats faster and becomes lighter. The 
heavier water then settles, leaving the free oil at the top. This is 
one of the reasons why heating coils are placed around the suction 
pipes in oil storage tanks. 

On a vessel of great depth it has been found necessary to install a 
relay tank between decks, in order to avoid the great head of oil that 
obtains when the storage tanks are being filled. This precaution is 

Digitized by 


Digitized by 


Digitized by 


Liquid Fuel 227 

in addition to the pneumercator system with gages and annunciators 
at the booster pumps to indicate proper filling and low oil level. The 
side filling connections discharge oil into the relay tank through 
quick-closing valves. The oil flows by gravity from the relay tank 
to the distributing manifolds and thence into the storage tanks. 
Pneumercator annunciators installed at the relay tank indicate when 
the tanks being filled have been filled to 95 per cent capacity. The 
relay tank is fitted with gage glass, an overflow spring-loaded relief 
valve, a vent pipe connecting directly to the atmosphere, and a pipe 
connecting all storage tank vents so that these tanks may vent or 
overflow into the relay tank. No greater head of oil than given by 
the level in the relay tank can be placed on the storage tanks by this 
overflow system. Where the relay tank is installed, emergency fill- 
ing connections at the vessel's side are provided, and these lead to the 
suction sides of the booster pumps. Proper relief valves are installed 
to prevent these pumps from putting a pressure on the tanks. 

Fuel oil is transported in three ways, namely : (1) By pipe lines ; 
(2) by tank cars; and (3) by tank ships or barges. 

1. Pipe Lines. — Crude oil is collected into reservoirs at the oil 
wells. It is gathered by " gathering lines '* into the " trunk lines,'* 
and is piped by these to refineries near the seaboard or to places 
where markets are favorable. As illustration of the extent of trunk 
lines, the five great oil companies operating in what is called the mid- 
continent field, centered about eastern Oklahoma, had 4320 miles of 
continuous lines in 1914, giving outlet to this field in Chicago, 111. 
(and to Atlantic seaboard) ; Port Arthur, Texas ; Baton Rouge, La. ; 
and Sabine, Texas. The trunk lines are generally 8-inch steel pipes 
laid about 18 inches below the surface of the ground and are provided 
with heavy-duty pumping stations, generally not over 40 miles apart, 
which force the oil at pressures of 600 to 800 pounds. 

2. Tank Cars. — This method of transporting oil is costly and is 
accompanied by delays, and requires the further use of barges where 
vessels cannot approach the fueling pier. 

3. Tank Ships and Barges. — From a naval point of view this 
method is convenient, economical, and necessary. The tank ships 
may be considered as mobile bases maintaining the naval vessels upon 
their stations, thus requiring fewer reliefs and bringing about more 
effective naval effort. Tank ships are necessary for commercial pur- 
poses to transport crude oil from foreign countries and to distribute 
crude oil or its products to the market centers. Barges are necessary 

Digitized by 


228 Mabikb and Naval Boilers 

for port loading and for port to port distribution. As indicating the 
importance of tank-ship construction it is stated that one-fifth of the 
steel-ship tonnage of this country (exclusive of that on the Great 
Lakes) at the close of 1917 was in the oil transportation service 
There were 170 steel ships. As to relative cost of transportation by 
the three systems, they are^ in order of cheapness of fuel-oil product, 
pipe line, tank ship, and tank car. At some eastern seaboard points 
the cost of transporting fuel-oil by tank car is double that by the 
pipe line. 

Naval interests are involved in the sources of supply, the transpor- 
tation and storage of crude oil, and in the preservation of a continu- 
ing supply for years to come. 

The Pneumercator.* 

This is an instrument invented by a Mr. Parks, of Philadelphia, 
for measuring the volume or weight of a liquid in tanks or reservoirs. 
It does this by air pressure within a balance chamber located in the 
tank, the pressure being dependent upon the height of liquid above 
an orifice in the balance chamber and being communicated to a 
mercury column by a very small pipe line. The essential elements 
of the instrument are: (a) Balance chamber; (b) a mercury gage 
calibrated in feet and inches and in corresponding weights or vol- 
umes; (c) a pump or other means for supplying compressed air; and 
(d) a control valve (see Fig. 91). 

The several positions of the control valve are : " Gage,'* *' shut,*' 
"air,*' and "vent" (as indicated on the valve). At "gage," the 
balance chamber communicates with the gage; at "shut," all open- 
ings are closed ; at " air," the balance chamber and the air pump are 
in communication ; at " vent," the mercury column is cut oflf. 

The installation and operation are as follows: The balance 
chamber is located so that its orifice is at a definite point near the 
tank bottom. The pipe is run to the locations where the readings are 
to be taken. The air pump is conveniently installed, as shown in Fig. 
90. When the tank is being filled, the control valve is placed at 
"gage," thus permitting the gage to indicate the rise of liquid. 
During the process of filling the control valve should be turned to 
" air " so that the level of liquid within the chamber may*be main- 
tained at the orifice of the balance chamber, this level tending to rise 

* From " Journal of American Society of Naval Engineers," May, 1916. 

Digitized by 


Liquid Fuel 











1 — 








— - 


— — — 

— « 

9 - 



_ _ _ 



— — 


: ^^j- 


,^^, ... 




r y 






— — 



Fig. 90. 


Digitized by 


230 Mabike and Naval Boilebs 

above the orifice and to cause inaccurate readings by the gage. A 
few strokes of the pump are necessary for this purpose. The control 
valve is now turned to " gage," and accurate readings are assured. 
A pipe is installed connecting the top of the gage mercury column 
with the particular tank that the gage serves. This assures accurate 
readings in case either pressure or vacuum exists on the tank. A 
duplicate column is provided for each tank at the gage board to oper- 
ate the annunciator, by low- voltage electric current; this annunci- 
ator indicating " 95 per cent full " and " low " levels. 

Fig. 91. — Pneumercator Control -Valve. 

Comparison of the Value of Goal and Oil as Fuel. 

To properly burn oil it is necessary to have a uniform steady 
pressure in the discharge oil spray. Several rotary and rotating 
plunger pumps have been designed to meet this condition. 

An illustration of each is given. 

(Inimby Screw Pump. — The general form and construction of 
the Quimby screw pump is illustrated in Fig. 92. The four screws 
that act as pistons in propelling the water are mounted in pairs 
or parallel shafts, and are so arranged that in each pair the thread 
of the screw projects to the bottom of the space between the threads 
of the opposite screws. The screw threads have flat spaces and 
peculiarly undercut sides; the width of the face and base of the 
threads being one-half the pitch. The pump cylinder fits the 
perimeters of the threads, as shown in Fig. 92a. Space enough is 

Digitized by 


Liquid Fdbl 281 





Digitized by 


232 Marine and Naval Boilers 

left between the screws and the cylinder and between the faces of 
the intermeshing threads to allow a close running fit \vithout actual 
contact. There is no end thrust on the screws in their bearings, 
because the back-pressure of the column of liquid is delivered to the 
middle of the cylinder and the endwise pressure upon the screws 
in one direction is exactly counterbalanced by a like pressure in the 
opposite direction. 

The suction connection is shown at S, Fig. 92, and opens into a 
chamber underneath the pump cylinder. The suction liquid passes 
through this chamber to the two ends, and is forced toward the 
center by the action of the two pairs of intermeshing threads; the 
discharge being in the middle of the top of the cylinder, as shown 
at D. The powder to drive the pump is applied to one of the shafts, 
and the second shaft is driven by means of a pair of gears, showTi 
at G, Fig. 92. 

The pump has no internal packing, no valves, and no small 
moving parts. The only packing is in the stuffing boxes, w^here 
the tw^o shafts pass through the cylinder heads. As these stuffing 
boxes are on the suction of the pump, there is no tendency to blow 
out the packing. 

Kinney Pump. — The general form and construction of the 
Kinney pump is illustrated in Fig. 93. The pump consists of a 
body B, a pump plunger D, placed eccentrically on a shaft C 

The operation of the pump is as follows : The shaft rotates in the 
direction sho\^Ti by the arrow. Oil enters at F into cavity H, As 
D revolves oil is forced around, through port E, and out at G. 

Plate XVIIIa is a line sketch showing the oil piping arrange- 
ment of a large oil-burning ship. Oil is drawn from tanks either 
forward or aft through manifolds by the booster pump. It is then 
picked up by the service pump and forced through the heaters to the 
boilers. Separate pipe lines are nm from manifolds to the hand 
pumps which discharge through suitable connections to boiler 
service lines. 

Theoretically, good coal evaporates 14.66 pounds of water per 
pound of coal, and good liquid fuel 19.9 pounds per pound. Theo- 
retically, the calorific value of 1 pound of liquid fuel is 1.36 times 
the calorific value of 1 pound of coal. 

A barrel of oil contains 42 gallons; a barrel of liquid fuel 16** 
Baum6 gravity, or .959 specific gravity, would contain 336 pounds, 
or 1 barrel of such oil would equal in calorific value 456.96 pounds 

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Liquid Fukl 




I I I • I . I I V 

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234 Marine and Natal Boilebs 

of good coal. 4.9 barrels of oil would equal 1 ton of coal. 

One ton of coal occupies about 43.6 cubic feet and 1 ton of oil 
about 39 cubic feet. 

If the same space could be used for oil that is used for coal^ 1.1154 
times as many tons of fuel oil could be carried as coal^ and this fuel 
would contain 1.517 times as many heat units as the coal. 

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Liquid Fuel 235 

If the boiler eflBciency remained the same with liquid fuel as it is 
with eoal^ the steaming radius of that vessel would be increased 
1.517 times with liquid fuel. 

Boiler Efficiency. — The boiler efficiency with liquid fuel is higher 
than with coal, for the following reasons : 

1. Liquid fuel can be completely burned with less excess of air 
than coal^ thereby giving a lower loss in chimney gases. 

2. There are practically no losses from waste of fuel, as there are 
with coal. 

3. The air supply and oil supply to the furnace can be kept con- 
stant, giving a constant rate of combustion with a constant furnace 
temperature, which cannot be maintained with coal. 

4. The boiler heating surfaces remain clean with oil. 
Therefore, the actual increase of steaming radius would be be- 
tween 1^ and 2 with liquid fuel over coal for the same speeds. 

BediLotion in Fire-room Force. — ^As there is no handling of coal 
or working of fires, the number of firemen and coal passers can be 
greatly reduced. A coal-burning battleship having a complement 
of 220 firemen and coal passers could, with oil fuel, have that com- 
plement reduced to about 50, which would be enough for operating, 
cleaning and repair purposes. The saving in pay and rations would 
be considerable, and the space now taken up for wash-rooms and 
lockers would be available for the remainder of the crew. 

Bapidity of Getting the Fuel Aboard. — Coaling a battleship re- 
quires from one to two days, with another day for cleaning ship, and 
it is an " all-hands '^ job. With oil fuel a ship can be fueled in 5 
or 6 hours, and it takes only a few men to do the work. A ship 
can easily be supplied with oil at sea, and the steaming radius of 
a ship is limited only by the amount of oil fuel in the fuel ships, a^ 
it would not require an entry into port for replenishing the supply. 

Oil More Efficient. — ^The excess of air, that comes with opening 
the doors for firing and cleaning fires when using coal, is avoided 
when using oil. As the pressure of air and oil can be regulated, it 
is possible to get better economy from oil firing, as the proportion 
of air for combustion is under control. More perfect combustion 
prevents formation of residuals and smoke, resulting in cleaner and 
more efficient heating surfaces. There is but little waste of fuel on 
starting up or shutting down. 

Storage of Oil. — Portions of a ship now useless for coal bunkers, 
through their narrowness or inaccessibility, are available for oil 

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Marine and Natal Boilsbs 

storage. The double bottoms are used as oil tanks, and this feature 
can be taken advantage of in trimming the ship. 

Advantages of Liquid Fuel for Karine Use. — 1. Oreater boiler 

2. Fewer men required in the fire-room force. 

3. Fewer weights to carry, such as firing tools, ash engines, buck- 
ets, etc. 

4. Glean boilers on the fire sides at all times. 

5. No fires to clean, no ashes to remove; therefore, greater fuel 

6. Oreater ease and cleanliness with which, and less time in which, 
it can be got on board and stowed in storage tanks, both in port 
and at sea. 

7. Less time in getting up steam. 

8. Steam can be controlled more easily. 

9. Practically no loss in getting up steam, standing by and com- 
ing to anchor. 

10. More fuel can be carried in the same space. It can also be 
carried in spaces that are waste spaces, such as double-bottom com- 
partments and other isolated compartments, where coal cannot be 

11. Less wear and tear on the boilers. 

12. Eeduction in the length of the .fire-room, as there is no space 
required to work the fires. 

Disadvantages of Liquid Fuel for Karine ITse. — 1. Greater cost. 

2. Bequires more care in handling to prevent fire and explosions. 

3. The supply is not general at present. 

4. Structural difficulties in connection with its safe and satis- 
factory storage. 

Combustion of Oil Fuel. 

The general principles of the combustion of fuel already discussed 
apply to oil as well as to coal. The essential difference between the 
burning of oil and the burning of coal lies in the greater ease with 
which theoretically perfect conditions can be realized with the 
former. The factors of high furnace temperature, sufficient quan- 
tity of air and ample combustion space assume greater importance 
with fuel oil than with coal ; but at the same time, these factors are 
handled with much greater facility in an oil-burning boiler than 
in one burning coal. 

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Liquid Fuel 237 

For the complete combustion of fuel oil^ the requisite conditions / 
are: (1) The oil must be broken up into minute particles (atom- ' 
ized) and sprayed from a burner before it is ignited; (2) the gases 
must be kept at the ignition temperature long enough to insure 
burning; (3) the air supply must be in sufficient quantity and of 
sufficient velocity to surround completely every minute particle of 
of oil and cause its complete combustion to.COj and HjO. 

The first condition is fulfilled by the use of atomizing burners 
previously described. The fineness of the atomization depends upon 
the pressure, of the oil^ the temperature of the oil^ and the design 
of the burner atomizing head. If the pressure and temperature 
of the oil are too low, the particles of oil may be too large for com- 
plete combustion, and some of the oil will then be deposited on the 
heating surfaces and furnace lining as soot and unbumed carbon. 

The second condition is fulfilled by having a large combustion 
space (furnace) with a thick brick lining on the bottom and sides. 
The large combustion space permits the gases to diffuse and the air 
to circulate around them, and retards the gases long enough to burn 
them completely before they strike the cool tubes. The brick lin- 
ing, when once heated, retains the heat and keeps the furnace tem- 
perature high in somewhat the same manner as the incandescent 
bed of coal in a coal-burning boiler. The bricks must be of the 
highest quality, and should be capable of withstanding a tempera- 
ture of 3200** F. 

The third condition is fulfilled by regulating the quantity and 
velocity of the air in the furnace bj_ means ot forced-draft blowers 
and. adjustable air registers. By regulating the speed of the blower 
and adjusting the shutter of the air register, the velocity of the air 
is made high enough to overtake and surround every particle of oil 
in sufficient quantity to bum it completely. At the same time, the 
air is given a whirling motion, so that it will mix more intimately 
with the gases and oil spray and not pass into the furnace in streams. 

Practical Kethods of Approaching theoretically Perfect Conditions 

in Burning Oil. 

Proper Atomization. — ^With the present fuel-oil installations in 
the U. S. Navy, a pressure of the oil in the burner of from 160 to 
200 pounds per square inch is required for proper atomization. At 
the Fuel-Oil Testing Plant in Philadelphia, a standard pressure 
of 200 pounds is maintained on all burners ; and when it is necessary 

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Marine and Naval Boilers 

to reduce the rate of combustion, some burners are cut out. If 
the burner is clogged with dirt or gum, or if the outlet hole in the 
tip is scored, the atomization will not be good. If the hole in the 
tip is increased slightly in diameter, there will be a great increase 
in the quantity of oil discharged. The opening in the navy stand- 
ard burner is only ^V in diameter. For use in port, burners of 
smaller capacity (smaller outlet holes in the tips) are supplied. 

Unless the viscosity of the oil is reduced to the proper point, the 
atomization will be improper, or nil, no matter how perfect the 
burner and how proper the pressure. With the oils now in use, it 
has bqen found, as previously stated, that the temperature must be 
raised enough to lower the viscosity to 8 on the Engler scale to 
insure proper atomization and smokeless combustion of the oil. 
Larger heaters are required for oils of high viscosity than for those 
of low viscosity. The heaters in general use in the U. S. Navy will 
reduce the viscosity to 8 if the viscosity is not greater than 200 at 
100^ F. 

Another point in connection with viscosity is that it must be 
reduced enough for the oil service pump to lift the oil and force 
it through the piping at a certain rate. With most of the fuel 
oil that has been used, it is generally not necessary to heat the oil 
in the storage tanks to pump it. Some oils, however, are too thick 
to flow freely enough to be pumped at ordinary temperatures, and 
have to be heated. Steam coils around the suction pipes in the oil 
tanks accomplish this purpose. It has been found by experiment 
that it is not necessary to heat any known oil above 105® F. to 
insure that the pumps will give sufficient supply for full power. 
If oils of higher viscosity are discovered and come into use, more 
heating will be necessary and change in the types of heaters and 
pumps may be desirable. 

Rotary pumps are best suited to maintain steady pressures at the 
burners. With the reciprocating pumps in general use, a steady 
])ressure is maintained by means of oil service-pump governors, 
by relief valves on the pump, and by air chambers on the dead ends 
of the oil service-pumj) discharge line to the burners. Oil absorbs 
the air in these chambers, and in practice it is necessary to re-charge 
them to a pressure of 90 j)0unds per square inch about twice a day 
in order to prevent fluctuations in the oil pressure and vibration of 
the oil pipes. 

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Liquid Fubl 

Keeping the Oases at the Proper Ignition Temperature. — Once 
the brick lining of the furnace is thoroughly heated, the furnace 
remains hot. Bricks must be secured from jarring loose by vibra- 
tion, the boiler casing must be kept air-tight (except through the 
registers), and the air supply must be kept as low as is consistent 
with economical combustion. The cone of oil particles sprayed from 
the burner should not strike the relatively cool water-containing 
parts of the boiler, for the oil spray would then be cooled below 
ignition temperature and, also, dangerous local overheating of the 
places of impact might result. The burners should be so placed in 
the registers as to secure the proper direction of the spray. If 
bricks are burnt up or jarred loose the furnace will cool and the 
casing may warp. The harmful effect of cold air leaking through 
the casing is due not so much to the cooling effect on the furnace as 
to the decrease in eflBciency of the heating surface on account of the 
low conductivity of this excess air. 

Proper Quantity and Velocity of Air. — The proper quantity and 
velocity of air are regulated by the blowers and by the shutters on 
the air registers. The quantity of air actually in the furnace may be 
sufficient for complete combustion, but there may not be enough 
movement to this air to supply more oxygen as some of the oxygen is 
consumed. (See chapter on " Combustion.'*) Hence, the air must 
be supplied fast enough to furnish the necessary oxygen. Therefore, 
the velocity of the air is the most important factor in its supply to 
the furnace. The quantity of air is sufficient when the flame of the 
oil is short, and yellowish-white. In the furnace, little flame is 
apparent; the gases of combustion are colorless, and the lines of 
division among the bricks in the bach wall can just be made out. 
There is then proper combustion. If the flame is pure white, and 
the back walls can be seen distinctly through it, there is an excess of 
air. If the flame is dark yellowish-red, there is insufficient air. 

Too much air gives white smoke from the smoke-pipe. Too little 
air gives black smoke. The quantity of air is about right when the 
smoke is a light brownish-gray haze — jiLst a feather of smoke. With 
nearly all registers in use, it is desirable to run with the shutters 
partly closed, as this gives better regulation of the velocity of the 
air. The amount of opening varies with the rate of combustion and 
the type of register. 

Insufficient air causes vibration or panting of the boiler casing 
and lining, and knocks down the brick-work. The vibration is due 

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24U Mabinb and Natal Boilebs 

to some of the unconsumed oil dropping to the bottom of the furnace 
and later forming explosive mixtures. If vibration occurs^ the 
blower should be speeded up imtil it ceases^ or else some burners 
should be cut out. 

While the color of the smoke and the flame is an excellent indi- 
cation of proper combustion, the only sure indication is an analysis 
by some gas apparatus such as the Orsatt 

The position of the burner in the air register must always be such 
that the spray will clear the brick lining surrounding the opening 
in the casing for the register, and in addition it should be further 
adjusted to get the best combustion with varying rates of power. 
The burners fitted with impeller plates should have the tips about 
1" in front of the plate for ordinary powers and about 2" in front 
for full power. 

Operation of Oil-Burning Boilers. 

Oil-burning boilers are normally operated, particularly at sea, 
under forced draft, using the closed fire-room system except in 
some battleships in port where th^ open fire-room system is used 
There is no prescribed limit to the air pressure, but between 6" and 
7" of water is necessary for full power. 

, In port, the practice varies. All three methods — ^mechanical 
atomization, air atomization pjid steam atomiz^tion — are used. 
SuflGicient data are not available to determine the relative merits of 
the several systems at the low rates of combustion required, but the 
tendency is toward mechanical atomization, with an occasional use 
of the forced-draft blowers in connection with it. 

Air atomization has the disadvantage of requiring heavy air 
compressors in conjunction with it, wear and tear on these com- 
pressors, and extra steam to operate them. 

Steam atomization has the disadvantage of waste of steam and 
the probability of the burners going out due to wet steam, with the 
residtant danger from a flare-back when the burner is re-lighted. 

To Start a Boiler — ^ITo Steam Available. — Make all necessary 
examinations and tests as to water, fittings, etc., required for all 
boilers; then: 

1. Take off stack cover. 

2. Open damper (if fitted). 

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Liquid Fubl 241 , 

3. Examine furnace to see whether any oil has dropped from a 
leaky burner. If so, wipe it up. 

4. By means of the' hand pump, bring up the pressure on the 
burner line to about 200 pounds per square inch, and keep it as 
steady as possible. 

5. Open wide the shutters to all registers to give as much air as 

6. Dip a torch made of a long rod, with asbestos ball wicking or 
waste on its hooked end, into a can of oil or kerosene, and light the 

7. Open the burner and light it, and keep the pump going con- 

8. Unless the oil is a light one whose viscosity is 8 or below at 
70** P., the torch will have to be kept up to the burner constantly 
until steam forms and the viscosity is reduced by heat to 8 or below, 
when the torch may be withdrawn. 

9. When steam has reached 75 or 100 pounds, put steam on the 
oil pumps and heaters and cut out the hand pump. 

10. Put steam on the forced-draft blower and get ready to light 
other burners. 

11. Start blower slowly and light off burners. 

12. As soon as the burner is lighted, speed up the blower until 
the air pressure is suflBcient to prevent vibration and flare-back. 

13. Close the shutter of the register to the proper opening (deter- 
mined by experiment with the particular plant concerned). 

If it is desired to prevent smoke, an excess of air will be needed 
until the furnace is well heated, when the proper quantity of air 
may be obtained by closing the registers the proper amount. 

If additional burners are required, adjust the air register for that 
burner to the proper opening, speed up the blower, and then light 
off the burner. If vibration results, cut out a burner until the 
blower can be speeded up enough to give suflScient air. 

Keep a half glass of water. If the water level is too high, the 
boiler will prime. 

As burners are added to a boiler, the water level rises, and vice 
versa. Never cut out all the burners at one time on a boiler operat- 
ing at full speed. The water level will drop out of sight, and, if the 
oil being used is a heavy one, the relief valve on the oil pump may 

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242 Mabinb and Natal Boilers 

stick and the high pressure in the oil line may rupture the pipe and 
cause a dangerous fire. 

(General Notes on Lighting Boilers. — ^If steam is available, start 
the blower and turn it over slowly to prevent any danger of flare- 
backs. Hold the torch to the wide-open vanes of the register, and 
open the burner valve wide. "WTien the burner is lighted, regulate 
the shutter opening and speed up the blower to eliminate smoke. 
Always light oflf the top center burner first, and then the adjacent 
burners in order, wing burners last. Warm up with two burners, 
and, if any more are desired, cut them in as necessary. If a burner 
is lighted under a boiler, other burners may be switched on without 
using a torch. Never try to light a burner from a red-hot back wall, 
as there is danger of a flare-back. When there is any blazing oil 
on the furnace floor, keep the blower turning over slowly to clear 
the furnace of gases before trying to relight a burner. When using 
only a few burners, use the center burners of the top row. 

Pull-power Conditions. — Running at full power with oil-burning 
boilers differs from running at lower powers only in so far as it is 
necessary to increase the oil pressure, maintain a high air pressure, 
and use as many burners as possible. 

Shutting down a Boiler. — 1. Shut off burners one at a time, wing 
burners first, then the bottom row, then the upper rows, and the 
top center burner last. 

2. Slow burners first before cutting out. 

3. Slow fuel-oil service pump. 

4. When all burners are shut off, close off oil supply. 

5. Close all air doors. 

6. Stop blower when it is certain that it has run long enough to 
blow all oil gas out of the boiler. 

7. Put on smoke-pipe cover. 

Oil as an Auxiliary to Coal. 

A few battleships in the U. S. Navy are fitted to bum oil in con- 
junction with coal. The installations for burning the oil, which are 
of a permanent nature, consist of the usual pumps, storage tanks, 
etc. ; there is a material decrease in the number of oil burners per 
boiler, the number of burners per boiler, on a battleship, being from 
three to eight. 

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Liquid Fuel 243 

The original idea, in fitting these ships to burn coal and oil simul- 
taneously, was that, in case of dirty fires, the oil fuel would aid in 
making temporary increases in speed. Such, however, has not 
proved to be true in practice, and the principal advantage of the 
double system is that more fuel can be carried by the ship, as oil 
can be stored in places not accessible for coal storage, and, by burn- 
ing oil alone strategical advantages may be gained on account 
of the greater steaming radius obtained. 

Some disadvantages of combining oil and coal as fuel are: (1) 
The combustion chambers are too small to burn the oil and coal 
together in an eflScient manner; (2) the coal fire cannot be properly 
tended when burning oil, as the flame shuts off a view of the top oi 
the fire; (3) the use of oil causes the clinker to fuse on the grate, 
making the fires very hard to clean; (4) it is a difficult matter to 
carry such pressures as will give the proper volume and velocity of 
air necessary for economical combustion, and it is impracticable 
properly to supply the requisite air to burn the oil sprayed above 
the coal fire on the grate; (6) the high fire-room air pressures 
necessary to give the proper velocity and volume would be injurious 
to boilers designed essentially for coal burning; (6) it is necessary 
to carry a complete outfit for each kind of firing. 

Special Notes in Begard to Fuel-Oil Installations. 

Dangers of the Oil-Burning System. — There are three principal 
dangers that may arise in an oil-fuel plant. (1) Flare-backs; (2) 
fires; (3) leak of oil to steam side of heaters and thence to boilers. 

Flare-backs are due to explosions of a mixture of oil gas and air in 
the furnaces. These generally occur at the time of lighting fires, 
and may result in serious injury to the fireman by burning; in addi- 
tion, the brick-work may be damaged and the boiler be put out of 
commission by the force of the explosion. The precautions neces- 
sary to prevent flare-backs are as follows : 

1. The furnace floors and any pockets in the boiler casing where 
oil can collect must be kept scrupulously clean and free from oil. 

2. There must be no ^eaks from the burners into the furnace. 

3. When lighting fires, the pressure in the oil service pipes must 
be high enough to atomize the oil completely as it leaves the burner, 
to insure that oil does not drip onto the furnace floor. 

4. If there is steam on the ship, the blowers must be running at 
the time the burner is lighted, giving a pressure sufficient to clear' 
the furnace of any oil gas that may be in it. 

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244 Mabinb and Nayal Boilbbs 

5. The fireman must use a long torch (at least 4 feet) in lighting 
a burner on a cold boiler^ to insure that^ in case a flare-back does 
occur, he will not be burned. 

Fires may be caused by the ignition of oil or oil gases in any place 
where oil accumulates by leakage from the system. Absolutely tight 
joints, with no leakage of oil, are necessary for safety; this must be 
impressed on everyone ; and leaks, when discovered, must be stopped 
immediately. Before using any part of an oil-fuel system, it should 
be tested to a pressure of 300 pounds with cold oil and be proved to 
be tight 

Oil spilled anywhere must be immediately wiped up. 

A box of sand should be kept in each fire-room to put out any 
oil fire. 

Oage glasses on oil tanks should be shut off except when readings 
are being taken. 

Fire extinguishers should be kept in fire-rooms, and a steam hose 
should be kept ready. 

Bilges should be inspected frequently for any collection of oil. 

It is a good practice to close tiie fire-rooms and run the blowers 
for a few minutes every day in order to expel any gases which may 
have accumulated in inaccessible places or around undiscovered 

Keep paint- work to a minimum; t. e., the boiler casings, pump 
barrels and everything else that can be kept bright should be so 
kept. On destroyers, the frames and plates in the boiler compart- 
ments are galvanized ; therefore, no paint is necessary ; but a careful 
watch must be kept to prevent corrosion where the frames or plates 
become exposed when the galvanizing wash is knocked off. 

Leaks of fuel oil into the feed-water system will occur whenever 
the pressure oil heaters leak and the oil pressure is greater than that 
of the steam. 

These leaks are detected by an examination of the water drained 
from the steam side of the heaters. When such a leak is discovered, 
the heaters are shut off and the oil is bypassed around them. 

Care of Burners. — ^Burners and burner tips, when not in use, 
should be kept covered with a thin coating of light engine oil. 

Before new burners are used, they should be tested out under 
water pressure and the cone of spray should be carefully examined 
for streaks. The streaks are caused by irregularities on either the 
'inside or the outside of the orifice, and should be eliminated by 

Digitized by 


Liquid Fuel 245 

polishing before the burner is used. If the streaks are not elimi- 
nated, an excess of air will probably be needed to run smokelessly. 
A stick of hard wood inserted into the orifice with a paste of oil 
and finely powdered glass will remove the streaks. Old tips should 
be periodically tested under water pressure, and should be replaced 
with new tips if badly worn. 

If, while under way, some burners are found to leak considerably, 
it is better to reduce the oil pressure and light more burners. 

Dirty burners cause smoke. 

Furnace Brick-work. — ^Extra good quality bricks and special 
high-heat cements must be used in the furnaces of oil-burning 
boilers. The joints between the bricks must be very carefully made, 
and the cement which protrudes from the joint must be smoothed 
back an inch or so from the joint, so that the sharp edges of the 
brick will not be exposed to the erosive action of the heat. The 
cement is first thinly spread over the entire surface of the brick, 
and, when the bricks are brought together, all air is expelled from 
the joint. When all brick-work is laid up, the entire surface of the 
furnace lining should be coated with a thin mixture of the cement, 
about the consistency of paint. The life of the brick-work is limited 
by the life of the joints. 

Bricks are bolted to the boiler casing, and the bolt holes on the 
inside are filled with cement. The best recent practice is to extend 
the bolts only part way into the brick-work (see description of B. & 
W. boiler. Chap. III). 

Air leaks. — It cannot be repeated too often that boiler casings 
must be tight for efficient steaming. Dead boilers in the same fire- 
room with steaming boilers must have all doors in their casings 
closed and must not leak. Air leaks not only reduce economy and 
injure steaming boilers, but also waste steam by necessitating an 
increase in the air pressure delivered by the blowers. 

Dangers from Use of Liquid Fuel. 

The dangers from the use of liquid fuel on board of naval vessels 
are very few: (1) If the tanks, piping and fittings are properly 
prepared and are thereafter kept in proper condition; (2^) if the 
fuel supplied has a flash pomt of 150*" F. or above; and (3) if the 
fuel is never heated above a temperature of 10^ below the flash 
pomt until it leaves the bumftr ; (4) if the fuel, wherever spilled or 

Digitized by 


246 Mabins and Naval Boilers 

allowed to overflow into bilges, is immediately cleaned up and the 
place is covered over with sand. 

The vapors from petroleum are explosive when mixed with the 
proper proportion of air, and are non-life supporting. Therefore, 
no one should ever enter a tank imtil the vapors have been blown 
out with steam or air; never without a life line around his body, 
nor without being attended by others on the cJutside; and never 
under any circumstances with an open light 

Fuel oil containing no sulphur or moisture will cause no corrosion 
or decay metals, pipes or brick-work, but will rot rubber, fabrics, 
concrete and paints. The amoimt of sulphur sufficient in oil to 
produce appreciable corrosion of the oil storage tanks has not been 
definitely determined. It is known that some oils containing as 
much as 4:ifi have been carried in steel tanks without any evidence 
of corrosion. 

Smoke Screen. — An important advantage of the use of oil fuel is 
the ability to make a smoke screen. This is done by reducing the 
amount of air supplied while the oil supply is kept constant. In 
practice a smoke screen is made by slowing the forced draft blower. 

Note. — ^For additional information on liquid fael» see Chapter XIV and 

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FrecautioxLB Prior to Lighting Fires. — Preliminary to lighting 
fires in any marine boiler^ using either coal or liquid f uel^ the pre- 
cautions that must always be taken are : 

1. There must be water in the boiler above the highest heating 
surface; the water should show in the gage glass for about one- 
quarter of its height. 

2. The gage-glass cocks should be tried and put in proper condi- 
tion if the gage glasses do not register correctly. 

3. The gage cocks should be tried and proved to be working 

4. The bottom and surface blow valves should be closed^ and all 
connections to the boiler should be examined and proved to be 
properly secured and ready for use. 

6. The smoke-pipe covers should be removed. 

6. The dampers to all idle boilers that connect through the 
breeching to a smoke-pipe in use should be closed tight. 

7. The smoke-pipe guys should be examined and, if set up taut, 
they should be slacked off evenly all roimd. 

8. All connection and dusting doors or the boiler must be closed 
and properly secured. 

9. The air cock on top of the boiler should be open. 

10. All cocks or valves on the line of steam to steam gage must 
be opened. 

11. The safety-valve hand-lifting gear should be operated to see 
that the valve is not stuck on its seat. 

On naval vessels, the engineer officer is generally given about 24 
hours notice as to the hour set for sailing; the speed that will be 
required ; the destination of the vessel ; and the probable nature of 
the steaming required; whether the vessel is to steam singly or in 
fleet, and if in fleet whether maneuvering is to take place. 

When steaming in company with other vessels, the senior officer 
present sets the ^^ standard speed '^ and all vessels must have steam 
enough to keep distance on the flagship and enough more to give 
them " full speed *' for a short time. 

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248 Mabins and Naval Boilbbs 

In fleet work, the standard speed having been set in the sailing 
orders, it is customary to get up steam in enough boilers to make, 
steadily, about two knots more than the standard speed. 

After getting his orders, the engineer officer knows from expe- 
rience, or by consulting the log book, steaming trial data or the 
engineer's note book, the number of boilers necessary to meet the 

Starting Fires and Getting up Steam in a Coal-Burning Boiler. — 
After the steaming orders are given to the engineer officer, he 
decides on the boilers to be used, generally using those that have 
been under steam the least since commissioning the vessel, unless 
there are good reasons to the contrary. He then orders these boilers 
primed and fires started at a certain time to have steam up to work- 
ing pressure, safety valves tested and engines warmed up and turned 
over with steam at about 30 minutes before the time set for getting 
under way. 

With fire-tube boilers it requires at least 6 hours to form steam 
and get it up to working pressure, without risk to the boiler; with 
water-tube boilers 3 hours are usually allowed, although steam 
can be raised in 50 minutes from the time fires are started, without 
much risk to the boiler. 

With fire-tube boilers in which hydrokineters are fitted, they are 
turned on 8 or 10 hours before fires are started and are kept on until 
steam is up to working pressure. A hydrokineter is an injector for 
circulating water in a large Scotch boiler. If fire-tube boilers 
are not fitted with hydrokineters, the auxiliary feed pumps are 
started at the same time as the fires, taking their suctions from the 
bottom blow-valve connections to the boiler and discharging into it 
through the auxiliary-feed check valve, thereby circulating the 
water in the boiler and allowing it to warm up gradually and evenly 
all over; the pumps should be run until steam forms. 

Fires are started in time to have steam up to working pressure, 
safety valves tested with steam and' all boilers connected to the main 
and auxiliary steam lines at least 1 hour before time set to get 
under way; this allows an hour for completely warming up the 
engines and trying them with steam, and, barring unforeseen acci- 
dents, assures being ready in every respect to get under way at the 
time set. 

Priming Furnaces. — If there is a boiler in use from which live 
coals can be obtained, the priming of a furnace consists in spread- 
ing a light layer of coal over the grates. If there is no boiler in 

Digitized by 


Firing 249 

use the grate in front of the furnace door is covered with wood and 
oily waste, in addition to the coal spread over the grate. All of the 
above preliminary precautions having been taken, fires are started 
by placing burning coal from a- boiler in use in the front of the 
coal-primed furnace, or by lighting the wood and oily waste at the 
front of the grate. The dampers are now opened, the furnace doors 
are opened slightly, and the ash-pan doors are closed. The fire will 
gradually work its way back over the whole of the grate and, as 
this occurs, more coal is added and the fire is gradually built up 
to the proper height. The fires may be hurried by opening the ash 
pan and closing the furnace doors ; they can be checked by closing 
the damper and the ash-pan doors. 

As the water in the boiler warms up, the level will rise and air 
will escape from the air cock and from the drain cock on the 
steam gage. When steam forms and can be seen blowing out of 
the drain to the steam gage, this drain cock and the air cock on 
the boiler are closed and pressure begins to show on the steam 
gage. If the gage does not inamediately begin to register a pressure, 
all of its connections should be examined and the reason for not 
registering be ascertained. 

Steam pressure now rises slowly and gradually, and the pressure 
is allowed to run up imtil the safety valves are blown with steam; 
the pressures at which they blow are recorded ; the damper and ash- 
pan doors are closed and the steam pressure is allowed to fall to a few 
pounds above that in the main and auxiliary steam lines. 

Connecting Boilers to Main and Auxiliary Steam Lines. — ^When 
there are independent main and auxiliary steam-line valves on the 
boiler and steam is on both of these lines, a boiler is connected to 
them when the boiler pressure is a few poimds higher than the 
steam in the line. If there is no steam in either of these lines, the 
lines are drained, drains to traps are left open, traps are bypassed, 
and the valve on the boiler is opened very slightly, allowing the steam 
line to warm up gradually and the pressure in it to rise slowly until 
the pressures in the boiler and the line equalize; the boiler stop valve 
can then be opened the proper amount and the bypasses on the traps 
be closed. After one boiler is connected to the main and auxiliary 
lines, the others are connected when their pressures are a few 
poimds higher than those in the lines. 

In connecting a boiler to the auxiliary or main steam line, the 
valve should be just moved off its seat until the pressures in the 

Digitized by 


260 Marine and Naval Boilers 

line and boiler equalize. If this is not done, serious water-hammer 
in the pipes may result, causing leaks in the pipe line, or rupture 
in the pipes. When the boilers connect to the auxiliary line only, 
and through it to the main line by-commimicating valves, all boilers 
are connected to the auxiliary line, as stated above. The communi- 
cating valves between the main and auxiliary lines, or bypasses 
around them where fitted, are then opened slightly until pressures 
equalize in the lines, when the communicating valves can be opened 
the required amount. 

In boiler management a thorough knowledge of the main and 
auxiliary steam lines, their valves, drains and other connections is 
absolutely necessary; and extreme care should always be taken to 
connect a boiler with any line only when the pressure in the boiler is 
nearly the same as that in the line, and then only by slightly open- 
ing (cracking) the valve imtil the pressures have equalized, before 
fully opening the valve. When turning steam from a boiler into any 
line, the drain valves on that line must be open, and the traps should 
be bypassed until the steam line is warmed up. 

Some superheaters are fitted, without drains, and in such position 
that water accumulates in them by condensation after boilers are 
disconnected. In such cases, when the volume of steam in the steam 
pipes is adequate, the connecting valves may be opened slightly 
when the boiler pressure is a few pounds below the pressure in the 
steam lines. Then steam passing from the line, through the super- 
heater, into the boiler, will blow the water from superheater back 
into the boiler. The stop valves are then closed again, and the 
boiler safety valves are tested. This procedure prevents carrying 
the water ^n the superheater over into the steam line, as would be 
the case were the boiler stop valves opened when the boiler pressure 
had been raised a little above the pressure in the steam line. 

Warming up the Engines. — Steam for warming up the main 
engines is taken from the auxiliary steam line through the cross- 
connection to the main steam line. 

Steam should form on all boilers at about the same time; shortly 
thereafter, the throttle valves are closed and steam from either the 
main or auxiliary lines is turned into the cylinder jackets. 

Water-tube boilers, as a rule, have only one steam connection, 
that to the auxiliary steam line, the auxiliary line connecting to 
the main line by communicating valves; therefore, the second 
method can be used only on a very few of the older vessels. 

Digitized by 


FiBINQ 251 

With large engines^ steam should be on the jackets and the engines 
should be warmed for at least 1 hour before they are moved with 

Large turbines are warmed by turning steam into them^ opening 
their drains and revolving the rotor witii the turning engine, with 
no vacuum in the condensers. Some turbines are started cold. The 
time of warming up is variable. 

ControlliiLg the Steam. — Formerly, when preparing to get under 
way, when coming to anchor or when standing by, steam pressures 
were controlled principally by means of the bleeders, which are 
bypasses from the main steam lines to the condensers. This practice 
has been proven to be injurious to the condensers, and therefore the 
present practice is to regulate or close the ash-pan doors and to 
further decrease the draft by using the dampers. Opening the fur- 
nace doors will check the production of steam; but this is likely to 
damage the boiler, as the cold air currents thus admitted cause 
unequal expansion, and such practice is forbidden. Throwing green 
cual on the fire will also check the steam production for a short 
period of time. Much of this coal is wasted, however, and it also 
builds up a heavy fire; so this method is no longer used. The ash- 
pan doors must be regulated with much care to avoid burning out 
the grate bars. 

When steaming in fleet, the steam pressures in fire-tube boilers 
are more easily controlled than those of water-tube boilers. The 
reason for this is that there is in the fire-tube boiler a much larger 
relative volume of water heated to the working pressure temperature 
than in the water-tube boiler. With a water-tube boiler a slight 
increase in the demand for steam causes the pressure to drop more 
quickly than the same increased demand would with a fire-tube 
boiler. Therefore, more care is required in controlling the steam; 
and in steaming in fleet where the speed is varying from time to 
time, team work is required between the machinist at the throttle 
and the water tender in the fire-room. The steam pressure falls 
more quickly on an increased demand for steam; it also rises more 
quickly when the demand for steam is decreased. 

Methods of Firing with Coal. 

Mechanical Stoker. — ^The ideal method of firing coal is the one 
in which the mechanical stoker is used. The mechanical stoker 
provides a more regular rate of supplying coal to the furnace and 

Digitized by 


252 Mabinb and Naval Boilers 

avoids the fluctuationfi of furnace temperatures caused by the open- 
ing of furnace doors when firing by hand. The rate of combustion 
and the furnace temperatures are, therefore, more nearly constant 
than can be maintained with the most methodical hand firing. The 
mechanical stoker is also more economical in the use of coal and in 
labor than hand firing. While there are many successful mechanical 
stokers in use imder shore boilers, the mechanical difficulties of 
fitting and operating them under marine boilers are so great that 
they are not used. Some of these difficulties are ; 

1. The spaces available for marine boilers are too small and too 
congested to allow proper installation of mechanical stokers. 

2. The motion of the vessel in a heavy sea has been found to 
prevent their operating properly. 

3. The rate of feed cannot be varied sufficiently to satisfactorily 
meet the requirements of naval vessels, with their great variations in 
rates of combustion. 

Hand firing is the only method now in general use for marine 
boilers. Naval boilers are not designed to get the maximum econ- 
omy in the use of coal; they are designed more with the view to get 
the maximum amount of steam possible per unit of weight. They 
have small furnace volumes, and are installed in contracted spaces. 
The difficulties of firing properly are great; the coal is burned in a 
furnace space of contracted dimensions, so that the gases of com- 
bustion come in contact with the heating surfaces, and are cooled 
below their ignition temperatures, before all of the combustible 
matter in them has been totally consumed. Smoke and loss of 
economy increase as the percentage of volatile matter in the coals 

The best way to explain the difficulties of obtaining high economy, 
with the ordinary furnace, from the bituminous coals when hand- 
fired, is to give the sequence of events that take place between two 
successive firings. When it becomes necessary to throw more coal 
on the grate, there is already on it an incandescent bed of coke, say 
6" to 8" deep. When firing, a few shovelfuls of coal, much of 
it of fine size, is spread evenly over the bed of coke. The first 
thing the fine coal does is to choke the air spaces existing through- 
out the bed of coke, shutting oflE the air supply, which is needed 
for burning the gases from the fresh coal. The next thing is a 
very rapid evaporation of moisture from the coal, a chilling proc- 
ess which robs the furnace of heat. Next is the formation ol 

Digitized by 


FiaiKo 253 

water gas by the chemical reaction, 0+H20 = CO-f-2H, the steam 
being decomposed, its oxygen burning the carbon of the coal to 
carbonic oxide, and the hydrogen being liberated. This action takes 
place when steam is brought in contact with highly heated carbon. 
This is also a chilling process, absorbing heat from the furnace. 
The two valuable fuel gases thus generated would give back all the 
heat absorbed in their formation, if they could be burned, but there 
is not enough air in the furnace to bum them. Admitting extra 
air through the fire door at this time will not accomplish the pur- 
pose, for the gases being comparatively cool cannot be burned unless 
the air is highly heated. After all of the moisture has been driven 
jff from the coal, the distillation of the hydrocarbons begins, and a 
considerable portion of them escapes unbumed, owing to the de- 
ficiency of hot air, and to their being chilled by the relatively cool 
heating surfaces of the boiler with which they come in contact. 
During all of this time smoke is escaping from the smoke pipe, 
together with unburned hydrogen, hydrocarbons and carbonic oxide, 
all fuel gases; while at the same time soot is being deposited on the 
heating surfaces, thereby diminishing their eflSciency in transmitting 
heat to the water. 

At length the distillation of the hydrocarbons proceeds at a slower 
rate, the very fine coal which at first obstructed the air supply is 
partially burned away, and suflBcient air comes through the bed of 
hot coke to bum thoroughly all of the gases. Such a balance now 
exists between the amount of gases generated and the amount of air 
supplied that the best possible conditions for maximum economy 
and smokeless combustion obtain. Finally, the gases are all distilled, 
and a bed of coke remains, which, as long as it is thick enough 
with relation to the air supply, will burn under good conditions for 
economy ; but, as soon as it bums down low and the air spaces be- 
come large enough to allow an excessive supply of air into the fur- 
nace, a new condition of poor economy is reached, the excess of aii 
passing up the chimney, carrying away heat which should have been 
utilized in the boiler. 

Conditions of Perfect Combustion. — Coal can be burned economi- 
cally without smoke provided that : 

1. The gases are distilled from the coal slowly. 

2. The gases, when distilled, are brought into intimate contact 
with a sufficient quantity of very hot air. 

3. They are burned in a hot fire-brick chamber. 

Digitized by 


254 Mabinb and Naval Boilbrs 

4. While burning, they are not allowed to come in contact with 
comparatively cool surfaces, such as the shell or tubes of a boiler; 
this means that the gases shall have sufficient space and time in 
which to burn completely before they are allowed to come in contact 
with the heating surfaces. 

In a few words, the necessary conditions for burning coal econom- 
ically and without smoke are : 

1. A sufficiency of air. 

2. The air must be brought into contact with the fuel, both solid 
and gaseous. 

3. The mixture of the gases and the air must be maintained for a 
sufficient time at a temperature of incandescence. 

The fundamental condition of perfect combustion of bituminous 
coals is that every particle of the gas distilled from the coal, includ- 
ing the water gas made by decomposing its moisture, be brought in 
contact with a sufficient supply of very hot air to bum it, the mixing 
of the gas and air taking place at a sufficient distance from the heat- 
ing surfaces of the boiler so that they do not become cooled below 
the temperature of ignition before the combustion takes place. 

Marine boilers are not designed to fulfil the above conditions. 
They have to be placed in contracted spaces, low down in the ships; 
they have to be made as light and as small as possible for the power 
required of them; the fire is always close to the heating surfaces; 
the combustion-chamber spaces are always contracted; from the 
nature of their use and the places they have to go, the fire-brick 
work has to be kept down to the minimimi limit, and the conditions 
generally are against maximimi economy with smokeless combustion. 
With the limitations in boiler design, the best that can be done is 
to select a good system of firing for that particular boiler and for the 
kind of coal generally used, properly train the firemen in the sys- 
tem, and see that the system is carried out. 

There are four systems of firing, each of which has its claims for 
recognition, and also its faults. The systems are as follows : 

1. Even-Spread Firing. — In this system, the fireman spreads the 
coal evenly, beginning at the back of the grate and working towards 
the door. The intervals between firing and the amoimt of coal fired 
at each time vary with the experience of the engineer in charge and 
with the kind of coal and amount of draft in use. Some coals bum 
better with a thick fire, with the coal fired in large quantities at 
long intervals; others give better results with a moderately thick 

Digitized by 


FiBiNQ 265 

fire^ using a shorter interval and a smaller charge of coal. The most 
economical methods of burning various coals uiider varying drafts 
can be determined only by experiment, and the economical working 
of the plant depends entirely on the attention given to these points 
by the engineer in charge- 
As regards efficiency, there is not much difference between a 
thick and a thin fire, unless it be too thick or too thin. If the fire 
be too thick, say over 10" to 12", with different coals, the air supply 
will be choked, and incomplete combustion with the formation of 
carbonic oxide will result; and the carbonic oxide will escape un- 
bumed with a great loss in economy. If the fire is too thin, say 
under 5" to 6", with different coals, holes are more liable to be 
burned in it, giving an excess of air, with a consequent loss of 
economy and, perhaps, damage to the boiler. The best thickness 
depends upon the quality and the size of the coal, the draft and the 
rate of firing. 

Objections to the even-spread system are as follows : 

(a) When the coal is spread evenly over the whole grate, the fine 
coal chokes the air passages through the bed of coke on the grate 
and reduces the air supply at the time when it is most needed to 
bum the water gas and hydrocarbon gases distilled from the fresh 

(b) When the coal is first fired, if spread evenly over the furnace 
the moisture in the coal is distilled from it, a cooling process which 
is taking place all over the grate. 

(c) The formation of water gas when the steam in (b) is brought 
in contact with the highly heated carbon on the grate is a cooling 
process and also takes place all over the grate. 

(d) The formation of smoke due to the incomplete combustion 
spoken of in (a). 

2. The Coking System. — ^In this system the fresh coal is piled 
on the front of the grate, while the rear half is covered with partially 
burned coke. The gases distilled from the fresh coal then pass over 
the rear half of the grate, through which an excess of air is entering, 
the air being highly heated as it passes through the bed of coke. 
The two gases, one containing the distilled gases, the other the 
neated air, intermingle in the combustion chamber, or in the com- 
bustion space of a water-tube boiler, and are completely burned to 
carbon dioxide and steam. When practically all of the gases are 
distilled from the fresh coal on the front half of the grate, it is 

Digitized by 


256 Marine and Naval Boilers 

pushed back over the rear half and levelled, and, either immediately 
thereafter or in a short space of time, fresh coal is again placed 
on the front half of the grate. With coals giving a very fusible ash 
in large quantities, the coking system cannot be used to advantage, 
for in pushing the coked coal to the rear half of the grate the coke 
and ash lying thereon (which may have been kept below the fusing 
temperature by the air passing through it) becomes mixed with the 
coked coal; the coked coal bums very rapidly just after being pushed 
back, generates a very high temperature, melts the ash and causes 
it to run and choke the air spaces in the grate, thereby decreasing 
the air supply and causing the coal to bum uneconomically. 

The coking system involves a greater amoimt of care and labor on 
the part of the fireman than the even-spread systeni. The extent to 
which the coking system produces economical smokeless firing de- 
pends upon the character of the coal, the skill of the fireman and 
the size of the combustion-chamber space. The lower the percentage 
of volatile matter and moisture in the coal, the less smoke will be 
made with any system of firing. 

If the charge of coal is kept small, the firing interval and charge 
kept uniform and the bed of coal at the back of the furnace kept 
level and not too thick, the firing will be economical and there will 
be little smoke. 

The larger the combustion-chamber space in which the smoky gas 
and the hot gas charged with air imite, the longer will be the time 
afforded for their mixture, and the result will be more complete 
combustion and decreased smoke. 

3. Alternate Side-Firing System. — This system seems to hieive all 
of the advantages of the coking system without its disadvantages. 
It consists of spreading fresh coal on one side of the grate over its 
whole length, then over the other side, altemately, at equal intervals 
of time. Instead of covering the whole grate with fresh coal at 
long intervals, only half of the grate is covered at each firing and 
the firing interval is shortened to one-half the time. After each 
firing the volatile gases from the fresh coal rise from it, and become 
mixed with the hot gases and hot air from the other half of the 
grate, resulting in more complete combustion and less smoke. With 
this system of firing, economical and smokeless combustion depend 
in a large measure upon the skill of the fireman, but more espe- 
cially upon the size of the combustion-chamber space and the op- 
portunity it affords for the thorough admixture of two currents of 

Digitized by 


Firing 257 

gas. Alternate firing is of no use unless there is ample combustion- 
chamber space in which the two currents of gas are mixed and the 
smoke is burned before the gases come in contact with the compara- 
tively cool heating surfaces. 

4. Alternate Front- and Back-Firing System. — ^This system is the 
same as that above except that the fresh coal is alternately fired on 
the front and back halves of the grate, instead of the right and left 
halves. The action of the gases is the same and the results are 
practically the same. 

Improper firing is probably the most common of all the man; 
causes of poor economy of steam boilers. Often the fact that an 
improper method of firing is being used can be ascertained by 
careful observation, but at times it can only be discovered by a 
series of systematic tests. 

No Particular System Adopted in the Navy. — Up to the pres- 
ent time no one of the four systems of firing described above has 
been adopted in preference to the others. The method of firing 
water-tube boilers having more than one door to each furnace ap- 
proaches very nearly the alternate side-firing system. That part of 
the furnace that can be fired through one door is covered evenly 
all over with coal at one signal to fire, and that through another 
door at the next signal, thereby keeping one part of the furnace 
covered with green coal while other parts are covered with coke. 

Economical firing has taken rapid strides in the past few years. 
The even-spread system is the only one in practical use in the navy 
in fire-tube boilers having only one door to a furnace, though there 
is reason to believe that more economy may result fiom the alternate 
back and front or alternate side firing; for it is probable that with 
these systems there will be better combustion of the volatile gases 
and smaller losses, on account of lowering the temperature below 
the ignition point when the fresh coal is thrown on. 

Bad Firing. — Much can be learned by observing the mistakes of 
others and avoiding them. Some of the mistakes made by ignorant 
or negligent firemen are: 

1. Putting too large a quantity of coal on the fire at a time, 
covering the fire so thick that the air supply is choked, resulting 
necessarily in incomplete combustion. 

2. Firing at irregular intervals, sometimes having the fire too 
thick, and again allowing it to bum so. low that holes are burned 
in it, or so low that a large excess of air is passed through it, 

Digitized by 


258 Marine and Naval Boilers 

diluting the gases of combustion, and thereby sending too much heat 
up the smoke-pipe and reducing the furnace temperature. 

3. Neglecting to cover the whole of the grate surface properly, 
allowing holes to burn m the fire at places and having the fire too 
tliick in others. This can result in having an excess of carbonic 
oxide and an excess of oxygen in the smoke-pipe gases at the same 
time, if the excess of air passed through the thin fire at one place 
and the excess of carbonic oxide formed where the fire is too thick 
are cooled below the temperature of ignition before they are mixed. 

4. Not keeping the fires properly cleaned, thereby choking the air 
supply and causing imperfect combustion. 

Errors in firing, requiring a series of boiler tests or an analysis of 
the smoke-pipe gases for their detection, are often committed by the 
most careful and intelligent firemen without any suspicion that 
they are in the wrong. These are: (1) Carrying the bed of fire 
too thick or too thin on the grate for the size of the coal and the 
force of the draft; (2) imskilful regulation of the draft. 

Good Firing. — ^The best method of firing is the one that will 
insure that the smoke-pipe gases contain no carbonic oxide (CO) 
and no hydrogen or hydrocarbon gases, and at the dame time con- 
tain not more than 6^ of free oxygen. 

The presence of combustible gases, even in very small quantities, 
in the smoke-pipe gases is a sign of imperfect combustion and the 
consequent loss of economy. The presence of from 4j^ to 6j< of free 
oxygen in the smoke-pipe is usually a necessary accompaniment of 
complete combustion. A greater quantity means an imnecessarily 
large supply of air, and consequently unnecessary loss due to heating 
the excess of air. The percentage of carbon dioxide in the smoke- 
pipe gas is not as good a criterion of the furnace conditions as would 
be obtained from a quantitative analysis of smoke-pipe gases show- 
ing the percentage of CO2, CO and 0. A wrong idea prevails that 
when the percentage of CO2 is as high as possible the boiler economy 
is a maximimi. This is true only when the analysis of the gases 
shows no CO, and only a reasonable amount of free oxygen, not over 
65^. The presence of any CO indicates a heat loss, which rises quickly 
with the rise in CO percentage. Table II B, Appendix, shows the 
large value of this loss. In some boilers, notably those on shore with 
large combustion chambers, the percentage of COj will run high, say 
up to 13^, and yet no CO will be present in the gases. In other 
boilers, where the combustion chambers are small, as soon as the CO, 

Digitized by 


FiKiNG 259 

percentage runs above a certain limit GO begins to show up in the 
flue-gas analysis^ bringing with it the large heat loss. This limit 
with the marine type of boiler is about lOjif of CO2. 

In order, therefore, to get the best results from a boiler some form 
of gas-analysis instrimient must be at hand by which the percentage 
of CO2, CO and can be determined. Then a good rule for eco- 
nomical firing would be : 

Keep the percentage of CO, as high as possible, consistent with 
the absence of CO and with the presence of in small amounts — 
never over 6^. These conditions can be fulfilled only from experi- 
ments made by the engineer in chaise of each individual plant. 

Where the thickness of the fire and the force of the draft are 
under the control of the fireman or water tender, as they are on 
board naval vessels, good results may be obtained with either thin, 
medium thick or thick fires, if the force of the draft is regulated 
in proportion to the thickness of the fires. The proper thickness 
of the fire and the proper force of the draft to be used with the coal 
on hand have to be determined by experiment, or by observation by 
the engineer in charge, to determine that force of draft and that 
thickness of the fire used that will give the best results. 

The best regulation of the force of the draft and the thickness of 
the fire is that which makes the hottest fire. If an integrating 
pyrometer giving the average temperature of the fire over the whole 
of the grate could be made, it would be the ideal indicator of the 
furnace conditions. Deficient air supply, causing imperfect combus- 
tion, and excessive air supply, causing too great a dilution of the 
gases of combustion, both tend to cool the furnace. The hottest 
fire that can be made is one in which the air is enough in excess 
to insure perfect combustion and no more. The hottest fire is also 
obtained when the smoke-pipe gases show by analysis from 4^ to 6^ 
of free oxygen. The analysis of the smoke-pipe gases, therefore, 
gives an excellent indication of the furnace conditions. 

Intelligent Supervision of Firing. — Competition has become so 
keen, both in the navy and on the outside, that it is imperative that 
those in charge of an engineering plant get the maximum efficiency 
from the fuel. 

Pointers on Firing. — 1. Keep a good, bright fire. The color of the 
flame should be a light yellow. When dark shadows are thrown into 
the ash pan, it is an indication that there is clinker formed on the 
grate, directly above; this clinker prevents the air from getting 

Digitized by 


260 Marine and Naval Boilers 

through, and results in incomplete combustion. Use the slice bar 
on such clinkers, removing them at once, and do not make a dirty 
fire wait on the clock. 

2. Avoid excess of air. The greatest loss in furnace practice is 
due to excess of air. The waste chargeable to this cause will prob- 
ably, in ordinary cases, be ten times that due to incomplete com- 
bustion. Excess air may enter in the following ways : 

(a) Through open furnace door. Place coal in the best posi- 
tion for throwing it in the furnace and work rapidly when the door 
is open. The COj charts show material reduction of COj when the 
doors are open. Any means of reducing the period of open door 
wiU pay. There is a great difference in furnace temperatures be- 
tween the conditions of open and closed furnace doors ; the resulting 
contractions and expansions are bad for the boiler. 

(b) Through badly fitting furnace doors and furnace fronts. 
The fit of the doors and fronts should be made good and kept in that 

(c) Through the grate. Keep all the grate covered and all 
the fire clear of holes, bare spots, hills and hollows. A bare spot on 
the grate is the worst enemy of the coal pile. 

3. There is no absolute rule as to the height of fire to carry. Fires 
for natural draft should be carried roughly from 8" to 10", and for 
forced draft a little thicker. A thin bed of fuel will admit more 
air to the furnace chamber than a thick one. It is a matter of 
pressure (draft), and resistance (thickness of fuel); there is a 
relationship between the two which must be studied with each fuel 
and each furnace to operate furnaces with the greatest economy. 
This relationship can best be studied by analyzing the gases of com- 

4. Find the draft and thickness of fire which will give best aver- 
age percentage of COj. Too high a percentage of COj entails a like- 
lihood of too much CO ; in addition to the CO, there is probably some 
unbumed hydrocarbon gases which are lost. 

5. When fires require slicing, slice them, and at no other times; 
the same applies to raking and cleaning. 

6. Use a time-firing device to fix the stoking interval, as it 
leads to uniformity. The device should not be used to regulate 
anything but the stoking interval, as the times for slicing, raking 
and otherwise working the fires must be dictated by human judg- 
ment. When the bottom of the fire is in bad condition, it requires 

Digitized by 


PiBINQ 261 

slicing or cleaning; when the top is in bad condition, it requires 
raking; trouble on one side of a fire cannot be cured by treating the 

Under natural-draft conditions, Bumot found that when burning 
about 11 pounds of coal per square foot of grate surface per hour, 
the efficiency increased as the firing interval and weight of charge 
were decreased. He found evaporative efficiencies as follows (ordi- 
nary coal) : 

With charge equal to 1 shovelful 9.64* 

With charge equal to 2 shovelfuls 9.38 

With charge equal to 3 shovelfuls 9.18 

With charge equal to 4 shovelfuls 8.91 

In this connection it has been found that if the boiler dampers 
are partly closed when the furnace door is open, the efficiency is 

7. Boiler dampers are the throttle valves of the draft, and should 
receive as much attention as the steam throttles, or any other con- 
trolling device in the plant. When the damper is closed, the vacuum 
in the furnace and passes of the boilers is decreased. The lever for 
regulating the dampers should be long, and- the more holes in the 
arc for regulating the position of the dampers the better. For con- 
trolling the steam supply, use the dampers and ash-pit doors — 
never open the furnace doors for this purpose, as it causes too much 
expansion and contraction. Never throw on green coal for checking 
the supply of steam; it does check the steam supply, is coal 

8. Leaks of air into the uptakes cause great waste of heat units. 
One of the most marked improvements in recent years in boiler 
economy has come from having tight boiler casings. The excess of 
air coming through these leaks is simply so much air to be heated, 
and the process cools the heating surfaces. Analysis of combustion 
gases near the furnaces and further on near the uptake will show 
whether there are uptake leaks. A lighted candle carried aroimd 
the joints will also show where there are leaks. The leaks can be 
stopped by some effective kind of cement or plaster. Some one man 
aboard ship should be charged with the regular duty of seeing that 
the casings are kept tight. 

No air should be allowed to flow through the passages of any 
boiler except at the furnace. 
The above pointers, used intelligently in connection with a fair 

Digitized by 


262 Mabinb and Naval Boilbrs 

knowledge of what chemical reactions take place in the furnace, 
should give economical firing. 

Sates of CombustioiL. — ^When considering the question of firing, 
one of the most important points is the rate of combustion, or num- 
ber of pounds of coal burned per square foot of grate per hour. The 
low limit to rate of combustion is that rate below which it is im- 
possible to go without allowing holes in the fire. 

When dampers are used with judgment, coal can be burned 
efficiently at a low rate. The standard rate of combustion in the 
Pacific fleet is 12 poimds per square foot of grate per hour. Ac- 
cording to Bankine, Deakin, Kennedy, Button, Goxe and others, the 
amount of air required for the complete combustion of coal de- 
creases with an increase in the late of combustion. This increases 
furnace temperature, increases efficiency of the heating surfaces, 
decreases temperature of gas in the smoke-pipe, and decreases the 
smoke-pipe losses. 

The decrease in the temperature of the escaping gases will not 
follow, if the increase in combustion rate is obtained by decreasing 
the number of boilers in use. It does appear to follow, however, 
if for a given boiler the same total amount of fuel is burned, the 
rate of combustion being increased by reducing the grate area. 
Tests show that by blocking oflf some of the grate area, and increas- 
ing the rate of combustion (by burning the same amoimt of coal as 
would have been burned on the whole grate), the evaporation per 
pound of coal has been increased as high as 16^. This resulted in 
the increase of CO2, and gave a boiler efficiency of as high as 75^ 
or 80j^. When the rate of combustion is high, the fires cannot be 
kept thin without loss of efficiency. For a given draft, the heavier 
the fire the less the rate of combustion ; but, for a fixed rate of com- 
bustion, the efficiency increases with the thickness of the fire up to 
a certain maximum allowable thickness. 

With a rate of combustion of 27 pounds, Richardson and Fletcher 
found efficiencies to vary with thickness of fire as follows : 

Thickness Evaporation per 

of fire. pound of coal. 

9" 10.77 

12" 11.23 

W 11.54 

Hutton states that, with forced draft, fires should be at least 10" 
thick to reduce excess-air losses. The stronger the draft, with con- 

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Bequent greater rate of combustion^ the thicker the fire should be. 
Where increase in capacity is desired, the fires should be carried 
thinner; with a given drafts the thinner the fire (without holes), 
the greater the rate of combustion. 

Experiments by reducing the grate area and correspondingly in- 
creasing rate of combustion gave the following results : 
Rate of combustion, 14 lbs. Lbs. of water evaporated per lb. fuel, 10.10 
Rate of combustion, 23 lbs. Lbs. of water evaporated per lb. fuel, 10.91 

There are times when the grate can be shortened temporarily; 
this reduces the reserve power, but according to experimental re- 
sxdts there is a gain in economy. 



Name of ship. 


o e » 

S " w 

■a*. C > 
* o «• o 


Type of boilers. 

Delaware . 

21.66 37.487 
19.217 ' 20.71 
12.24 I 14.5 

Utah 21.04 80.47 

I 10.22 I 18.48 
12.02 I 15.525 


24.S26 ' 42.96 
22.668 29.47 
12.225 , 19.95 

Chester 26.522 I 55.08 

; 22.782 I 25.95 
12.20 I 17.63 


29.177 64.84 
24.14 i 82.85 
16.135 ' 22.166 










































B. & W. fitted 
with super- 

B. &W. 

Fore River ex- 
press type ; re- 
turn flame. 



Normand re- 
turn flame. 

• E^raporation from and at 212* F. for ships that are starred in this column is 
worked from the data given on the trial trips, using the temperatures of the feed 
water and pressures of steam at the boiler as given in the Journal of the Society 
of Naval Engineers. No account is taken of the quality of the steam, as the data 
in regard to It are not given, and probably were not recorded. 970 B. T. U. is used 
as latent heat of steam at 212* F. in these calculations. 

Utah's values from test of B. and W. boiler for Arkansas and Wyoming, Birm- 
ingham and Chester values from evaporative tests run during competitive trials 

* Natural draft 

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264 Marine and Naval Boilesbs 

Cleaning Fires. — In six or eight hours after fires have been 
started in a boiler^ depending on the character of the coal and the 
rate of combustion^ the grate bars begin to choke with ashes and 
cinders. This can be seen by a casual observation of the under side 
of the grate bars. When the fire is clean and burning properly, the 
under side of the grate will show bright all over it; but when the 
fires are dirty and the grate bars are choked, there will be dark 
patches under the choked portions, which are easily seen as they 
throw shadows in the ash pan. When it is seen that the fires are 
becoming dirty, the cleaning of the fires is begun; and during the 
remainder of the run the fires are cleaned regularly every 12 hours, 
or more often if necessary. The fires to be cleaned each watch are 
marked, and the division is made so that each watch will clean one- 
third of the fires in each boiler. In a boiler with two furnaces, with 
three doors to each, one fire from each furnace should be cleaned 
each watch. When a fireman sees that there are clinkers in any of 
his fires, he should remove them as soon as they are discovered, 
whether it is his fire to clean or not. 

When the ash-hoisting engine was the only means of clearing 
the fire-rooms of ashes, the practice in cleaning fires was for the 
watch going off to burn down the fires that its relief was to clean. 
The new watch would then clean its fires as quickly as it could be 
done, while maintaining steam at the proper pressure. The chief 
water tender gave directions as to how many fires were to be 
cleaned simultaneously. The practice of allowing the watch going 
off to burn down the fires for the relief is bad, especially so when 
steaming in fleet. The fires, when burned down, are not in the 
proper condition to make steam, and practically one-third of the 
fires are in that condition. With water-tube boilers, an increased 
demand for steam demands its immediate production, and if the 
ship drops out of position when the fires are burned down or at 
any time before they are all cleaned and are burning up properly, 
it is impossible to regain the position until the fires are all in 
proper condition. For a watch to bum down the fires its relief is 
to clean sometimes leaves the relief in such a position that it does 
not get its fires up to proper condition during the whole of the 
watch. Prior to the installation of ash ejectors, fires were cleaned 
early in every watch, for the job of clearing the fire-rooms of ashes 
was a long one, and therefore much effort was made to get all fires 
cleaned and ashes ready to hoist as soon as possible after the watch 
came on. 

Digitized by 


PiBING 266 

The better practice, especially with water-tube boilers steaming 
in fleet, is to let each fireman burn down the fires he is to clean, 
under the supervision of the chief water tender ; the fires will then 
be cleaned in rotation, steam pressures will not be allowed to fall, 
and, with ash ejectors as now installed, the ashes can be sent over- 
board at any time during the watch after all the fires in that fire- 
room are cleaned. 

The limit to the number that can be cleaned simultaneously is 
governed by the steam pressure, and by whether all other fires are 
burning freely. If the steam pressure is low, or the boilers are not 
steaming freely, only a few fires can be cleaned at one time. 

In cleaning the fire, the good coal and coke is shoved to one side of 
tfie furnace and the clinkers are raked out of the furnace and wet 
down with the hose provided for the purpose. If clinkers stick to 
the grate bars, the slice bar is used as a pry to loosen them. In case 
of clinkers sticking to the grate bars near the furnace front, the lazy 
bar placed across the furnace front can be used as a fulcrum, mak- 
ing a lever by the slice bar. Clinker near the rear of the furnace 
is pried off by raising the fire-room end of the slice bar. All tools 
must be at hand and everything must be ready before starting to 
clean a fire, so that the time taken to do the job will be as short as 
possible. When one side of the furnace is cleaned, the good coal and 
coke is shoved to the clean side and the other side is cleaned. After 
cleaning a fire, spread the burning coal and coke and cover the bare 
places with fresh coal, and fire lightly until the coal is burning freely 
over the whole furnace area; then build the fire up gradually to 
normal thickness. 

Hoisting Ashes. — The ashes in the ash pit should be hauled fre- 
quently, and the ash and clinker from cleaning fires should be re- 
moved from in front of the furnace to some place near the ash hoist 
or ash ejector, care being taken that they are not piled against any 
bulkhead plates. Boards, put against the bulkheads temporarily, 
make a good protection. When the ashes have been removed, the 
guard plates on the boiler front, the front of ash pits, and the fire- 
room floor in front of the furnace should be swept clean. This will 
prevent the accimiulation of wet ashes and leave a clean place for 
the next round of coal. 

The older types of naval vessels have steam ash-hoist engines. 
On this type the fire-rooms are usually cleared of ashes at five bells 
of the watch. The ashes are hoisted to a deck above the water-line. 

Digitized by 


266 Mabinb and Nayal Boilers 

trollied by the deck force over to the side of the ship and dumped 
through ash chutes. Most of the newest ships are supplied with 
ash ejectors^ and this means of clearing the fire-rooms of ashes will 
be understood from the description of ash ejectors. 

When hoisting ashes under forced draft in a closed fire-room^ 
some care must be taken to keep the proper door of the tube or 
ventilator^ through which the bucket is hoisted or lowered^ closed 
to prevent the escape of air. By using the bell and speaking tube 
fitted for communication between the fire-room and the deck^ this 
can be done easily^ and also much unnecessary noise and delay be 

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It has been shown in the discussion of combustion that it requires 
a certain definite number of pounds or cubic feet of air to furnish 
the requisite amount of oxygen for the complete combustion of each 
pound of fuel; also that the complete combustion of a pound of 
fuel generates a certain definite number of heat units^ depending 
upon the nature of the fuel. The capacity of a boiler^ then^ for 
generating steam at a definite pressure^ the grate area and heating 
surface being fixed^ depends upon the rate of combustion (the num- 
ber of pounds of fuel burned in its furnaces per hour) . The rate of 
combustion depends upon the draft, which is the supply of air to 
the fires. 

Smoke-Pipe Draft, Natural Draft. 

The draft produced by the smoke-pipe alone is due to the fact 
that the gases inside the chimney are hotter and consequently lighter 
than the outside air. The pressure of the air at the top of the 
smoke-pipe^ due to the atmosphere above that leyel^ is the same on 
the gases on the inside of the smoke-pipe as on the air outside. The 
pressure at the bottom of the smoke-pipe^ on the inside, is the sum 
of the pressure of the air at the top of the smoke-pipe and the pres- 
sure due to the column of hot air in the smoke-pipe. The pressure 
at the same bottom level on the outside of the smoke-pipe will be 
that at the top plus the pressure due to a column of cold air as high 
as the smoke-pipe. The difference of these pressures inside and 
outside is considered to be the natural draft, in all theories of 
smoke-pipe draft. 

Calculation of Natural Draft. — To illustrate the calculation of 
the draft or difference of pressure due to any assumed conditions, 
we will take an example. The smoke-pipe is 80 feet high above the 
grate; the temperature of the gases in it is 450® F.; and the tem- 
perature of the air outside is SO"* F. The draft is calculated as 

The weight of a cubic foot of air at 32** F., and at the average 
atmospheric pressure of 14.7 pounds per square inch, is about .0807 
pound. The weight of air at a given pressure is inversely propor- 

Digitized by 


268 Marinb and Naval Boilebs 

tional to its absolute temperature (469.6** H-degrees F.) . Therefore, 
the weight of a cubic foot of hot gas and of a cubic foot of cold 
air in the example taken are : 

Hot ga8=.0807x ^^^,=M36 pound. 
Cold air =.0807 X ^^^'^^^^ =.0735 pound. 

4:017.0 "4" oO 

A column of hot gases 80 feet high and 1 foot square will weigh 
.0436 X 80 = 3.488 pounds and will give that pressure per square foot 
on a diaphragm at the level of the grate. The cold air outside will 
give a pressure of .0735x80=6.88 pounds per square foot. 

The difference of pressure, or the draft, will be 6.88—3.488= 
2.392 pounds per square foot, or 2.392-5-144 =.0166 pound per 
square inch. 

The hot gases of combustion at a given pressure and temperature 
have a slightly greater specific gravity than air at the same tem- 
perature and pressure ; but the diflEerence is very slight and may be 

A variation in the prrssure of the atmosphere and of its tempera- 
ture will affect these pressures, and the draft in the assimied smoke- 
pipe will vary with them. 

To find the draft in inches of water instead of pounds, we con- 
sider that 1 cubic foot of water weighs 62.4 pounds; consequently 
a colimm of water a foot square, which produces a pressure of 2.392 
pounds per square foot, will be 2.392 -^ 62.4 =.0383 foot high, or 
.0383x12 =.4696" high. The draft in the example given above, 
.0166 pound per square inch, equals .4696" of water, practically i" 

Limitations of Natural Draft. — This amount of pressure will 
drive only a certain definite quantity of air into the furnace in a 
unit of time, and therefore the nimiber of pounds of coal per square 
foot of grate per hour that can be burned in the furnace is corre- 
spondingly limited. 

We should therefore, with natural draft, be restricted in any 
given ship to a given amount of steam produced by the boilers, 
the variation in this amount being small and depending chiefly 
on the weather conditions, and should consequently be limited to a 
certain speed, as was the case in the earlier warships. 

If the height of the smoke-pipe were made greater, the draft 
would be increased, and consequently the amount of coal burned, 
or the rate of combustion, would be greater. This rate of combus- 

Digitized by 


Dkaft, Natural and Fobged 

tion is expressed in pounds of coal burned per square foot of grate 
surface per hour. But the smoke-pipe cannot be lengthened indefi- 
nitely, the usnal height on large ships now being about 100 feet 
above the grate surface. With this height, the coal consumption 
may be as much as 20 pounds per square foot of grate per hour 
under natural draft. 

Increasing the number of boilers would increase the amount of 
steam produced, but the weight and space of the boiler installa- 
tion would also increase. But as the weight of, and the space 
occupied by, the machinery (which includes engines, boilers and 
auxiliaries) on board modem warships are very important factors, 
the nimiber of boilers is limited. 

Forced Draft. 

We must, therefore, increase the steam-producing power of the 
given boilers by artificial means, and this is done by increasing 
the rate of combustion by the use of some system of forced draft, 
which term includes all degrees of increase in the rate of com- 
bustion when produced by artificial means. Some form of forced 
draft is all the more necessary on most modern high-powered 
ships, as, owing to the fitting of a protective deck and the very 
restricted openings left in it for air to reach the fires, natural draft 
is almost an impossibility. 

Not only is the steaming power of the boiler increased by the 
use of forced draft, but, when moderately applied, the efiiciency of 
the combustion is increased. 

The systems now in use are: (1) Steam jet; (2) closed ash pit; 
(3) induced draft; (4) closed fire-room. 

Steam Jet. — This system is the easiest to fit; but on account of its 
waste of steam, it is used only on steam launches or small boats, 
which can easily renew the fresh water lost. The steam is drawn 
from the boiler and blown through small holes in a pipe into the 
base of the smoke-pipe, or above or below the grate, thus induc- 
ing a current of air to follow from the outside. To overcome 
the waste of steam, compressed air has been tried, but its use is 
very limited. 

Closed Ash Pit. — ^Air is forced by centrifugal fan blowers, rotat- 
ing at high speed, through ducts into the ash pit and furnace, 
the openings oi which are tightly closed. It is an efficient and 
generally a simple system, and permits open fire-rooms. With 

Digitized by 



Marinb and Naval Boilbbs 

fire-tube boilers, as on the Monadnoch and Montgomery, the air 
ducts are led under the fire-room floor to the front of each ash pit, 
where they end in a casing which covers the ash-pit opening and 

Fig. 96. 

Pia. 97. 

which is provided with a door in front and a damper on a level with 
the bottom of the ash pit. 

This system is not now installed in armed vessels of the United 
States Navy. 

Digitized by 


Drapt, Natural and Forced 271 

The general principles of this system will be understood from 
Pigs. 96 and 97, which show the general arrangement. Pig. 96 is 
a front elevation of the lower part of the boiler, and Pig. 97 is a 
vertical longitudinal section through the center of the furnace and 
ash pit. The ash pit AA and furnace have been shortened for con- 
venience. The furnace door is shown at I; the ash-pit door, at 0; 
and the duct through which the air enters, at G. 

The door is made air-tight by an asbestos gasket secured 
around its edges, this gasket being slightly compressed when the 
door is lowered into the sockets below and the three wedge bolts 
above are secured by their handles. The furnace door I fits closely 
around its edge to the furnace front, and is held in that position by 
the handle H. The small slicing door S, being of heavy cast iron, 
allows BO air to escape, except a little under very strong draft. 

The damper B at the back of the ash pit is shown open, the 
dotted lines showing its position when closed. Connected to the 
spindle on which B moves, and on the outside of the boiler cas- 
ing, is the crank F, which is moved by the handle L, to the right 
of the furnace door, by means of the rods D and and the cranks 
at E. L has a curved projection on its under side, which, in the 
position showif, is held firmly against the top of the furnace door 
handle H. L has motion upward in the slotted arc, and can be 
held firmly in any position by the handled lock nut to the right. 
H cannot be raised nor the furnace door I be opened, until the lock 
nut on L is eased and L is raised, and then B must close and the 
air be shut off. 

Howden's System. — This is a closed ash-pit system, but com- 
bined with means for heating the air before it reaches the fires. 
The air heater consists of a nest of thin tubes fitted in the up- 
take, the products of combustion passing through the tubes, and 
the air for combustion passing around them. Special provision is 
made for the regulation of the air supply above and below the grate. 

When the system is fitted to fire-tube boilers, the grate is made 
shorter than usual, and it is level or slightly raised at the back. 
In addition to these changes, both generally conducive to econ- 
omy, the boiler tubes are fitted with retarders. These consist of 
strips of thin metal, twisted into a spiral, which are pushed 
loosely into each tube. By retarding the egress of the gases, and 
thus keeping them in contact with the tube surface for a longer 
time, more heat is abstracted, and increased efficiency follows under 
forced combustion. 

Digitized by 



Makinb and Naval Boilbrb 

All of the ducts and casings must be kept air-tight, or the hot 
air will be forced into the fire-room. 

As this system utilizes all of the means which have been shown 
to be necessary to economy and perfect combustion, it follows that 
when it is properly worked, the boiler efficiency will be increased. 

Fio. 98. 

Fig. 98 shows a side elevation, partly in section, of the arrange 
ment of this system on a Thornycroft boiler. The boiler casing is 
shown complete in the middle part of the boiler, and is removed at 
the top and bottom. 

Digitized by 


Dbaft, Natubal and Fobcbd 273 

B is the blower situated at the top and on one side of the boiler. 
The air heater is composed of 416 tubes, 2^" in diameter, and has 
a heating surface of 793 square feet, or a little over ten times the 
grate surface. Air ducts H, H are built on the front and back of 
the boiler to guide the air to the furnace fronts and to openings in 
the back wall and back of ash pit, as shown by the arrows. The 
products of combustion pass upwards from the furnace, around the 
boiler tubes, and through the tubes of the air heater into the up- 
take U. 

Above each furnace door F is an opening covered by a flat valve 
W, which can be moved by a handle from the outside. The supply 
of air to the front par); of the fire can thus be regulated. In the 
back wall, some distance above the grate, there is a perforated plate 
extending almost the whole width of the grate. By means of the 
damper V, the supply of hot air from H to the top of the fire can 
be regulated. The main supply of air enters the ash pit A through 
the large damper V. Both dampers are worked together by the rod 
L from the front of the boiler. A handhole jB is provided in the 
back of the casing for the easy examination of damper V\ 

Induced Draft. — This name applies properly only to the system 
by which an upward current of air through the boiler is induced 
by means of a blower at the base of the smoke-pipe, or in the up- 
take of each boiler. The blower required is much larger than that 
for the closed fire-room system, and is very liable to dangerous 
overheating. When a separate blower is fitted in each uptake, 
the draft can be regulated for each boiler separately as required. 
British naval experience showed that, while on other grounds there 
is little choice between this induced, or Martin's, and the closed 
fire-room system, the great advantages of working with an open 
fire-room remain with the induced draft. 

The most prominent ships fitted with this system are the British 
battleships Magnificent and Illustrious. The system is not used in 
the U. S. Navy. 

Ellis and Evans' System. — ^This is an induced-draft system with 
closed ash pits, combined with means for heating the air for com- 
bustion. In the latest type of this system, the air is drawn past 
the outside of the heating tubes, as in Howden's. As the pres- 
sure of the air is less in the casings and ducts, these need not be so 
carefully fitted. Arrangement is made for air distribution above 
and below the grate, similar to Howden's, but better. 

Digitized by 


274 Mabinb and Nayal Boilsbs 

. Heating the air for combustion results in' economy if the heat 
which is used for this purpose would otherwise be wasted. Thus, 
if the heat which is radiated from the boiler casing is used to heat 
the air for combustion, the result will be increased economy^ because 
of the resulting higher furnace temperatures, other conditions re- 
maining constant. 

Closed Fire-Eoom System. — This system is now more generally 
in use on warships than any of the others. In this system, the air is 
forced by blowers directly into the fire-room, all hatches and doors 
being closed air-tight, and must find its way out through the fur- 

It has these disadvantages: (1) The arrangement of air locks, 
ventilators, bunkers and special air-tight bulkheads is costly, and 
the weight is considerable. (2) The men are imprisoned in the 
fire-rooms by numerous doors and hatches, and must work in an 
atmosphere surcharged with coal dust. 

Communication between the fire-rooms, or between the compart- 
ments under pressure and those not under pressure, is effected 
by means of air locks. These are small spaces, each closed by two 
doors. After passing through the first door, it is closed before 
the second one is opened, thus reducing the loss of pressure to an 
inappreciable quantity. 

In order to reduce the fire-room space, which must be kept under 
pressure, special air-tight bulkheads are often fitted. With water- 
tube boilers, the ash pit and other air doors in the casing are 
so arranged that they will close automatically in case of a sudden 
outrush of steam, such as would follow the bursting of a tube. 
One form of this door is shown in Fig. 23, the axis on which it 
turns being above the middle of the door. It is held open in any 
position by means of the counter-weight at the top of the door, and 
by the notched lever. It is closed automatically by the excess pres- 
sure on the larger area. In another form, the door is inside the 
casing and hangs from supports which are well above the opening. 
The air pressure swings the door open, and any steam pressure 
would close it. 

Air-Prcssure Oages. — The usual method of measuring the air 
pressure or the draft, is by the difference in level of the water 
contained in the two legs of a glass IJ-tube, one end of which is 
open to the atmosphere and the other to the fire-room or air duct 
under pressure. 

Digitized by 


Draft, Natural and Forced 275 

Fig. 99 shows the ordinary air-pressure gage, without its case. 
The top of leg A is led to the atmosphere when this gage is used 
with the closed fire-room system, B being open to the fire-room. 
When the closed ash-pit system is used, A is con- 
nected to the air duct near the ash pit, B being 
then open to the atmosphere in the fire-room. 
Scale C is graduated in fractions of an inch to rep- 
resent the difiEerence of level or pressure, the zero 
mark being in the middle of its length or height. 
When there is no pressure, the water level should 
be at zero. If it is not, water should be added or 
taken out in order to facilitate the reading of the 
scale. It will be readily understood that a pressure 
exerted on the water level in B, which will force 
it down 1", will raise the level in A 1", and that the 
pressure is equal to that of a colimm of water 2" 
high. This is, therefore, the air pressure in the 
fire-room or air duct. 

The scale may be more conveniently arranged 
for reading by adopting a sliding scale, graduated 
from zero up. When a difference in the two legs 
is shown, the zero of the scale is put opposite the * 
lower level, and the reading of the air pressure «. g^ 

is taken from the higher level. No attention 
need then be paid to the quantity of water in the U-tube. 

As the air pressure is frequently given in otmces (per square 
inch), it will be well to show the relation between inches and ounces. 

A cubic foot of fresh water at 62° P. weighs 62.355 pounds; or, 
a colunm of water 1728" high and having an area of 1 square inch 
will weigh the same, or, in other words, will exert a pressure of 
62.355 pounds per square inch. Therefore, 1 pound per square inch 
would be exerted by a column 1728-^62.355 = 27.712" high, or 1 
ounce per square inch would be exerted by ^ column of water 1.732" 
high. Taking the reciprocal of this, 1" of water column is equal to 
a pressure of .577 ounce per square inch. 

Kate of Combustion. — So long as the amount of coal burned 
per square foot of grate surface under natural draft was sufficient 
for the requirements of the time, no especial effort was made to 
use forced draft, although all systems had been tried on naval 
vessels long ago. When, however, the desire for increased speeds 

Digitized by 


276 Mabinb and Naval Boilers 

became paramount^ following the introduction of the torpedo boat, 
forced draft was again taken up, about 25 years ago. The first 
object was to obtain higher powers with a given boiler; and later, 
to increase the economy of combustion. 

Under natural draft, which is usually considered to be equiv- 
alent to an air pressure of about i", the rate of combustion varies 
from 15 to 25 pounds, the latter being reached under most favor- 
able conditions. Following Mr. Thomycroft's experiments witli 
a closed fire-room, in which from 80 to 120 pounds and even 
more of coal were burned per square foot of grate, requiring air 
pressures of from 4" to 8", the rate of combustion on larger ships 
was much increased for a time. But leaky tubes and a general 
failure of boilers led to a steady reduction of air pressure, so that 
now the limit allowed for our large ships is 2". Torpedo boats and 
destroyers are not, of course, so limited, 5" and 6" being usual, 
although the limit for the later destroyers is 4^". At this latter 
pressure, the rate of the combustion varies from 55 to 66 pounds 
with the best coal. With air pressures ranging from i" to I'', the 
rate varies from 30 to 40 pounds. 

Significance of Draft in Boiler Practice. — The word draft relates 
to the fiow of gases through the boiler furnace, gas passages and 
stack. It is rather loosely applied in practice, and hence may not 
be accurately defined. As shown previously, the fiow of gases 
between two points is caused by a diflEerence of pressure existing at 
these points. In the case of natural draft this difference in pres- 
sure is due to the difference in weight of a column of hot gases and 
an equal colimin of cold air. With forced draft the difference in 
pressure is due to the increase in pressure in the fire-rooms (or at 
the ash pit) over the atmospheric pressure at the stack. In either 
case, the resultant fiow of gases is due to a pressure difference. 

The difference in pressure between the air at the ash pit and the 
gases in the uptake is called the total pressure drop through the 
boiler and furnace. This pressure drop is measured in inches of 

The difference in pressure between the air in the fire-room (c 
ash pits) and the gases over the fuel bed is called the pressure drop 
through the ftiel led. 

The difference in pressure between gases over the furnace and the 
gases in the uptake is called the pressure drop through the boiler. 

Method of Measuring Pressure Drop. — Pressure drop is generally 

Digitized by 


Deaft, Natukal and Foboed 277 

measured by means of ^-tubes^ one leg of each tube extending into 
the gas passage and the other end being open to the atmosphere. 
The difference in reading of the U-tubes will then indicate the 
pressure drop between the points at which the tubes are installed. 
If there is a considerable vertical distance between the two U-tubes^ 
the pressure drop must be corrected for the difference in atmospheric 
pressure between the two points. For example, if one tube is 30 
feet above the other, the apparent pressure drop (diflference in 
CT-tube readings) must be corrected for the vertical height by adding 
about .48" of water to the pressure drop — or the equivalent weight 
of a column of air 30 feet high. 

Effect of Pressure Drop. — If the total pressure drop remains 
constant, the pressure drop through any part of the gas path will 
increase with the resistance, while ine weight of gases .flowing 
through that part in a definite time will be decreased. Thus, if 
the fuel bed is doubled in thickness, or density, the pressure drop 
through the fuel bed will be doubled but the amount of air flowing 
through will not be increased. 

Practical Value of Pressure Determinations. — If the pressure 
drops through the fuel bed and through the boiler are measured, 
fairly accurate determinations may be made of the proper thickness 
for fires and the times for cleaning fires. Thus, if the pressure drop 
through the fuel bed is excessive, there will be too little air passing 
through the fuel and too little draft through the boiler, resulting in 
poor economy. The remedy is a thinner fire, or cleaning the fire 
if needful. Any decrease of air through the fuel bed due to clinker 
or the formation of a crust on the surface of the bed is indicated by 
the increased pressure drop through the fuel bed. 

Forced Draft for Liquid Fuel. — With the systems of burning 
liquid fuel now in use, forced draft is a necessity, especially so with 
mechanical atomization, and with these systems the construction of 
the furnace and the method of admitting the air are of equal and 
paramount importance. The oil spray is generally thrown off from 
the tip of the burner in the form of a cone. Thfe air for combustion 
should be given a whirling motion around the oil spray, and there 
should be suflBcient air to surroimd each particle of the fuel com- 
pletely and cause its complete combustion. The direction of the 
rotation is immaterial, but the velocity and method of controlling 
and producing the whirling air current are of vital importance in 
their effect on the combustion, and also on the shape and character 
of the resulting flame. 

Digitized by 



Marine and Naval Boilers 

The air current should have a velocity enough greater than that 
of the oil spray to enable the air to overtake the particles of oil and 
completely surround them. The quantity of air per pound of fuel 

Fio. 100.— Koertlng Patent OU-Firing System In Boilers of Torpedo- 

Boat Destroyers. 

need then be only slightly more than sufficient to cause the complete 
combustion of the fuel. It is the aim of the designer to obtain the 
required results with the least air pressure possible. 

Digitized by 


Dkaft, Natural and Foboed 279 

Fig. 100 shows the fitting of the boiler front of a torpedo-boat 
destroyer boiler. The fittings here described represent in a general 
way the manner of fitting all types of air registers and fuel oil 
burners in the boiler fronts of those U. S. naval vessels whose boilers 
are fired with oil only. Limited space necessitates modifications of 
burners, shape of spray, air supply thereto, etc., in boilers designed 
to bum coal with oil as an auxiliary fuel. 

The outer casing A has automatic air doors B, admitting air 
under pressure into the space between the inner and outer casing. 
The air is admitted to the burner through the air register and 
slide 0, which has slots cut in its periphery, covered by an outer 
casing with similar slots in it ; this outer casing is moved around the 
inner casing by the regulating handle D, thereby regulating the 
amount of air entering the furnace. The amount of air depends 
upon the amount of opening of the slots in and upon the pressure 
of air in the fire-room. The regulating handle D works a rod 
carrying a pinion, which engages a rack on the outer casing of C. 

The air pressure on destroyers using liquid fuel is carried as high 
as 6" of water. 

The maximum efSciency with desired steam pressure is readily 
maintained by altering the draft pressure with the oil supply. Any 
great increase or decrease of capacity should be taken care of by 
lighting or extinguishing additional burners, each of which has its 
individual air register and slide, so that it can be turned on full 
when the burner is lighted, or shut off entirely when it is extin- 
guished, the air pressure in the fire-room being increased or de- 
creased accordingly by controlling the speed of the blowers. 

The closed fire-room system is used entirely on our liquid-fuel- 
buming destroyers. 

The proper continuous control of the oil fiame is very important, 
not only on the score of economy and efficiency in making steam, but 
also as a tactical feature in the making, or discontinuance of smoke 

Digitized by 




Corrosion is essentially the dissolving of metals and is generally 
accompanied by the subsequent oxidation of such metal in solution. 
It may take the form of a fast coating over the entire surface, called 
general corrosion, or it may be restricted to small areas, in which 
case it is termed pitting. 

Causes. — Corrosion is due principally to the tendency of metala 
to dissolve in water, aqueous solutions and films of moisture. Tho 
metal so dissolved is readily oxidized in contact with free oxygen 
in the solution or above the surface of the solution. Three theories 
have been advanced to account for this action. All theories agree 
^at the presence of moisture and oxygen are necessary conditions. 
The three theories are: 

(1) The Acid Theory of Corrosion. 

According to this theory, corrosion can occur only in the presence 
of carbonic acid or of some other acid in solution. It is supposed 
that such acids start the corrosive action and act as carriers of 
metal to oxygen, maintaining the process indefinitely. It has been 
shown, however, by numerous experiments, that corrosion may take 
place when iron is immersed in pure distilled water from which all 
carbonic acid or other acids have been expelled. 

(2) The Hydrogen Peroxide Theory. 

This theory is based on the assumption that the formation of 
hydrogen peroxide is a necessary step in the formation of rust. 

Experiments, however, show that while hydrogen peroxide does 
induce corrosion, it is not essentially a factor in all corrosive actions. 

(3) The Electrolytic Theory. 

The electrolytic theory is based on the fact that all metals tend 
to go into solution. This tendency to go into solution is electrolytic 
in character and is due to a difference of potential existing between 

Digitized by 


CoRBOSio>J AND Watkr Trbatmbnt 281 

the metal and the solution or between two metals immersed in the 
same solution and metallically connected. A difference of potential 
between two points on the surface of the same metal is sufiScient to 
cause the metal to dissolve, provided the solution is of lower poten- 
tial than one of the points. 

For example, if two metals are metallically connected in the 
presence of an electrolyte, one of them dissolves while the other is 
protected, the whole process being accompanied by an electric cur- 
rent flowing from one metal through the solution to the other metal. 
Where there is a single metal only in the solution, the different 
points on the surface which are at different potentials act in reality 
like different metals. 

Metal so dissolved is readily oxidized by any free oxygen in the 
solution and is precipitated as rust, thus allowing more of the metal 
to dissolve. 

The electrolytic theory is generally accepted, but a detailed dis- 
cussion of it is beyond the scope of this work. It must be remem- 
bered, however, that a thorough understanding of the principles 
involved is essential to their practical application, and much damage 
may be done through ignorance and unintelligent application of the 

Experimental Besult?. 

Corrosion in Distilled Water. — Experiments made with iron 
strips immersed in chemically pure distilled water show that corro- 
sion occurs at varying rates, the amount of rust formed being 
dependent upon (1) the purity of the metal, (2) the amount of 
oxygen present in the water, and (3) the temperature of the water. 
In general, the amount of corrosion will depend directly upon the 
amoimt of oxygen having access to the water and present in the 
water. Impurities in the iron, points of high potential on the 
surface due to the working of the metal, and the amount of carbon 
present in the metal, all influence the rapidity of corrosion. 

Experiments have been undertaken with the view of excluding 
the air from the water by means of a protective film of oil on the 
surface. This method has proved ineffective, however, since the oil 
absorbed oxygen from the air and further transmitted it to the 

If all air is excluded from the water no corrosion occurs, but 
as soon as air is allowed access to the immersed metal, corrosion 
occurs rapidly. 

Digitized by 


Mabikb and Naval Boilers 

When pure distilled water is made sufficiently alkaline^ no corro- 
sion occurs^ but there is always the danger here that if the solution 
is not kept sufficiently alkaline, pitting will occur. It has been held 
that chemically pure iron immersed in pure distilled water will not 
corrode, but since chemically pure iron is not commercially obtain- 
able, and must also be free from internal strains and improper 
hanmiering, it need not be considered. 

The CorrosiYe Effect of a Couple Immersed in Solution. — When 
two different metals are metallically connected and immersed in 
water or an aqueous solution, a difference of potential will be set up 
between them similar to that in a battery, and if this potential is 
sufficiently great (depending on the character of the metals), one 
of them will dissolve while the other will be protected. Thus, in a 
copper-iron couple the iron will corrode while the copper will be 

If zinc is connected to iron and immersed in an aqueous solution, 
the zinc will corrode and protect the iron until the zinc becomes 
coated with zinc oxide, after which the action ceases. 

It has been maintained that since zinc oxide is electro-negative to 
iron, the current will be reversed and the iron will corrode faster 
than if no zinc oxide were present, but this contention has not been 
sustained by experiment. 

The temperature of such couples immersed in solution has an 
important bearing on the amount of corrosion which will occur, 
since the electrolytic potentials of metals and solutions, and the 
amount of oxygen in solution, vary also with the temperature. In 
general, the difference of potential between metal and solution will 
increase with increase of temperature. The temperature at which 
maximum corrosion takes place is about 160° to 180° F. 

The Effect of Acids on Corrosion. — If an acid is present in the 
solution, the corrosive effect is increased, and the rate at which 
corrosion progresses under such circumstances depends directly upon 
acid strength of the solution. 

It is worthy of note, however, that a piece of iron dipped in 
fuming nitric acid will resist corrosion for reasons which have not 
as yet been satisfactorily explained. This protection is only tempo- 
rary, however, and has no practical application. 

Corrosion of Alloys. — The electrolytic potential of an alloy is dif- 
ferent from that of any of its constituents, generally lying between 

Digitized by 


GoBBOSiON AND Watek Trbathent 283 

Bronze and brass alloys generally have a low potential and hence 
are not readily corroded by salt water. This makes naval bronze a 
good material for use on under-water fittings of ships, such as out- 
board delivery valves, etc. 

The Effect of Sodium Chloride.— Sodium chloride (NaCl), which 
is present in distilled sea water, has a marked effect on corrosion. 
By increasing the conductivity of the water the corrosion is ac- 
celerated. Where steel or iron is protected by being in metallic con- 
tact with zinc, the result of NaCl in solution is to increase the pro- 
tective effect, and extend it over a greater area. 

If boiler water is made sufficiently alkaline by the addition of 
soda, lime or other compounds, corrosion will be prevented. The 
necessary alkaline strength in distilled water free from NaCl has 
been found to be about S^ of a normal solution. When sodium 
chloride or other salts are present, a higher alkalinity wUl be neceS" 
sary, depending on the amount of salt present in solution. 
* The use of alkalies for this purpose is dangerous in one particular. 
Just before the point at which corrosion is prevented is reached, the 
rusting will be confined to a few spots and will take the form of 
pitting. U the alkalinity is never allowed to exceed 0.6^ however, 
pitting will not take place, and this alkalinity will insure that the 
water does not become acid. 

Keeping the alkalinity at 0.5^ will not prevent corrosion entirely 
if any oxygen is present in the water; but pitting will be prevented, 
and such corrosion as does occur will be general and not so dangerous 
to the safety of the boiler. 


Seasons for Treating Boiler Water. — There are three reasons for 
treating boiler water, viz.: (a) To render it as nearly non-corro- 
sive as possible, (b) to prevent the formation of scale, (c) to prevent 
the rise of surface tension and consequent priming caused by the 
impurities in the water and by the application of the remedies for 
(a) and (b). Surface tension is the molecular action of a liquid 
which resists any force tending to break through the free surface. 
This causes priming in boilers by its resistance to the flow of the 
steam bubbles through the surface, and therefore the boiling action 
is more violent and particles of water are carried over with the 

Digitized by 


284 Marine and Naval Boilers 

Boiler Compounds. 

Boiler compoiuids are mixtures of electrolytes, which, when dis- 
solved in feed water, are claimed to fulfill the requirements given 
under (a), (b) and (c) in the preceding paragraph. There are 
many boiler compounds on the market of various degrees of merit ; 
some of them are very good, but all are injurious if used without 
the proper degree of intelligence. 

Experiments show that good homogeneous steel immersed in dis- 
tilled water corrodes almost equally over its wetted surface. As the 
concentration (t. e., the percentage of normal alkaline solution) 
is increased by the addition of an electrolyte such as boiler com- 
pound, the rate of corrosion is at first slightly decreased, and after 
a certain concentration is reached, the rate of corrosion is increased. 
An electrolyte is a substance which increases the electrical conduc- 
tivity of water when the substance is dissolved in the water. At a 
certain definite concentration the rate of corrosion reaches a maxi- 
mum, and then falls off rapidly as the concentration increases, 
reaching a definite point at which corrosion ceases, provided no salt 
is present in the water. If any salt is present in the water, a higher 
concentration will be necessary before corrosion is prevented, the 
concentration necessary to prevent corrosion increasing with the 
amount of salt in solution. 

It is evident, from this, that it is better to use no treatment than 
to use any chemical or compound without knowing, by test pieces, 
whether the water is actually corroding the boiler metals. The 
method of using such test pieces is described later in tiiis chapter. 
There is also the danger that the saturation concentration will be 
reached and the chemical will be deposited as scale. This, however, 
is not probable with the Standard Navy Boiler Compound. 

The following are some of the qualities required in any com- 
pound used in the treatment of boiler water : 

(1) It must contain one or more metallic elements that have a 
higher electrolytic potential than the material of the boiler, prevent- 
ing the metal from going into solution. 

(2) It must contain some strong alkali to make the water alkaline 
at low concentrations. 

(3) It must be incapable of being broken down into other com- 
pounds giving acid reactions within the range of temperature to 
which the boiler water is subjected. 

(4) It must be soluble at these temperatures. 

Digitized by 


Corrosion and Water Treatment 285 

(5) It should Dot be coDducive to primiDg by iDcreasing surface 

(6) It should coDtaiu some cheDiical coDipouud which will com- 
biue with aDy scale-formiug elemeuts aDd keep them iu suspeusioD 
as sludges. 

The chemicals geoerally used are alkalioe earth metals, due to 
their high solubility, high solutiou tension and low cost. Solution 
tension is a measure of the tendency of metals to dissolve when 
placed in aqueous solutions. 

Composition of Boiler Compounds. — Sodium carbonate (Na2C03) 
is found to be one of the best agents in the treatment of water to 
prevent corrosion. Fig. 102 shows the results of tests at the Engi- 


J^ S.5 S5 />S5 X>OS3 u?OOS3 oo&occ ^^fmr 

Grams of chemical in one liter of solution. 
FiQ. 102. 

neering Experiment Station, Annapolis, Md., by putting pieces 
of steel in water treated with various amounts of NajCOg. The 
treatment periods were of 30 days each. The curve is the average 
of 12 periods. The solutions were made in distilled water. C" is 
normal solution (defined on page 289). In addition to sodium car- 
bonate^ lime is sometimes used as an electrolyte, but this has the 
disadvantage of being conducive to priming and is liable to be 
precipitated. Caustic soda and di-sodiura phosphate are also used 
in some boiler compounds. 

Digitized by 


286 Marinb and Naval Boilsbs 

A boiler compound which, under tests, seems to be very satis- 
factory was evolved during 1910, at the Engineering Experiment 
Station, Annapolis, Md. It consists of (1) 95^ calcined sodium 
carbonate (NsjCO,) ; (2) 4j^ di-sodium phosphate (Na,HP04, 
I2H2O) ; and (3) 1;^ of cutch or catechu. The first ingredient 
makes the solution non-corrosive, the second prevents priming 
and the third prevents formation of scale. The cutch is an or- 
ganic compound containing 40^ to 45^ of tannic acid; this has 
the property of preventing formation of scale, as it converts the 
foreign salts of the water from crystalline to colloidal state, and 
holds them in suspension within the range of boiler temperature. 
Starches and dextrines also have this property. The function of 
the di-sodium phosphate is to prevent the surface tension that 
causes foaming and priming. In addition, both sodium and potas- 
sium are very soluble and very high in the solution tension series. 
Distilled water was treated with the above compound and made 
non-corrosive ; the solution had 3^ normal alkaline strength. Evapo- 
rated to dryness, baked and treated with the original amount of 
distilled water, the'compoimd all redissolved. 

Impure Water. 

We will now take up the subject of impure water, the precipitates 
formed by the action of heat and the chemical action of the com- 
pounds used to render the water non-corrosive, and the treatment 
required to change these precipitates into their colloidal form and 
hold them in suspension in the solution. 

Water appears in nature in two forms : (1) That of the ordinary 
state, that of the water of crystallization in compounds precipitated 
from ordinary water solutions. 

The purest water f oimd in nature is rain water after it has rained 
for a time ; the first rain that falls absorbs the impurities in the air 
and is, therefore, impure: 

As soon as rain water comes in contact with the earth and 
starts on its course to the sea, it begins to dissolve various sub- 
stances according to the nature of the soil with which it comes in 
contact. Streams that flow over sandstone beds contain exception- 
ally pure waters, as sandstone is very insoluble. Those that flow 
over limestone beds dissolve some of the stone and the water 
becomes **hard.*' The many varieties of natural mineral waters 
are due to substances from the earth being dissolved in the water. 

Digitized by 


Corrosion and Water Trbatkent 287 

All natural water is, therefore^ more or less impure^ and the impuri- 
ties vary with the nature of the soil in the territory through which 
it has passed. In order to get pure water it must be distilled and 
kept free from air. 

WJjen pure distilled water is used in boilers, the treatment re- 
quired is (1) an electrolyte to raise the potential of the solution 
and prevent the metal from dissolving, and (2) one to prevent the 
high surface tension that causes priming. 

Natural water from limestone localities contains calcium acid 
carbonate in solution ; when the water is heated this is converted to 
calcium carbonate (CaCOs) and precipitated. At 300'' F. it is 
practically all precipitated as a sludge, if the water contains no 
other impurities. If it contains calcium sulphate or magnesium 
carbonate or sulphate, it forms a hard scale. With the magnesium 
and calcium sulphates, as they are precipitated, calcium carbonate 
sludge acts as a binder, cementing them into hard scale. Water 
from localities containing magnesium compounds dissolves magne- 
sium in the form of the acid carbonate and the sulphate. Magne- 
sium carbonate precipitates as a magnesium hydroxide (Mg(0H)2), 
which is soluble only to about i grain per gallon. Magnesium 
sulphate (MgS04) is quite soluble at boiler temperatures, but in 
the presence of CaCOg it forms magnesium carbonate (MgCOg) 
and calcium sulphate (CaS04), both of which are only slightly 
soluble. In presence of sodium chloride (NaCl) it forms very 
soluble sodium sulphate (NajjS04) and magnesium chloride 

Calcium sulphate is found in natural waters, and under ordinary 
conditions of temperature it is soluble to about 100 grains per 
United States gallon. Its solubility decreases with a rise in tem- 
perature, and at about 300° F. it is practically all precipitated. 

Streams that flow through localities contaming salt (NaCl) 
contain it in solution in comparatively large quantities. 

Natural fresh waters have in them, as the principal impurities, 
carbonates, sulphates and chlorides in quantity in the order 
named. The principal carbonate is the acid carbonate of calcium 
Ca(HC03)2, the principal sulphate is that of magnesium MgS04, 
and the principal chloride is that of sodium NaCl. The metals 
calcium, magnesium and sodium are cations in electrolytic dis- 

Sea Water. — Sea water contains the impurities contained in the 
waters emptying into it and those absorbed from the soil of its 

Digitized by 


288 Marine and Naval Boilbrs 

The average* composition of the water of the oceans ifl about 3.5;^ 
salts and 96.6j^ water. 

Compounds Found in the Sea Water. 

Salt— sodium chloride NaCl 

Magnesium chloride MgCU * 

Magnesium sulphate MgSO« 

Magnesium brgmide MgBrt 

Potassium sulphate KbSO« 

Calcium sulphate CaS04 

Calcium carbonate CaCO. 

Composition of Salts Found in Ocean Water (about). 

Per Cent. 
NaCl 77.76 

MgCl, 10.88 

MgSO* 4.74 

CaSO« 3.60 

K,S04 2.46 

CaCO, 34 

MgBr, 22 

The maximum percentage of salts foimd in sea water is 3.737%, 
the average percentage 3.5;^. The mean density of sea water is 

The percentage of salts in sea water may range from 1 to 4, but 
the percentage of each salt has been found to remain practically 

The principal impurities in sea water are chlorides, sulphates 
and carbonates in the order named. It may be seen that the order 
of the salts as to quantity in. sea and natural fresh waters is just 
reversed. Sea water dissolves only %Z% as much oxygen as does fresh 
or distilled water. 

It is now seen that the scale-forming ingredients in water, both 
natural fresh water and sea water, are the calcium sulphates, calcium 
carbonates and magnesium hydroxides. When sea water is treated 
with sodium carbonate, enough of it must be added to the water to 
precipitate all of the salts with whic}i it will react, and then enough 
more to bring the normal alkaline strength of the solution up to a 
certain definite percentage. This percentage has been found to be 
about 2.6 for ordinary good steel boiler plate. The reactions that 
take place when treating sea water with sodium carbonate are as 
follows : 

Digitized by 




Mineral salts in 
■ea water. 

Chemical with 
which sea 
water is 

Compound formed 
that is insoluble 
within the range 
of temperatures 
of boiler water. 

Compounds formed that are 
incompletely soluble within 
the range of temperatures 
of boiler water until near 
the point of saturation. 








NaCl and NasCO. 



KaCOa Na^SOf 

These insoluble salts are all precipitated at a temperature of 
300"^ F. as calcium carbonates and magnesium hydroxide^ the car- 
bonate of the magnesium compound being transformed into carbonic 
acid gas and driven from the water as COj at temperatures above the 
boiling point. These^ then, are the compounds that must be con- 
verted into their colloidal states and prevented from forming hard 
scale on the heating surfaces. This is done by the cutch in a boiler 

Notes on Solutions in General. 

Valence is that property of an element by virtue of which its 
atom can hold a definite number of other atoms in chemical com- 

(1) If a chemical compound is an acid, its valence equals the 
Dumber of replaceable hydrogen units it contains. 

(2) If it is a salt, its valence equals the number of replaceable 
hydrogen units in the acid from which the compound was formed. 

(3) If it is a base, its valence equals the number of. hydroxy! 
(OH) units in it from which the hydrogen of water has been dis- 

Examples of Valency. 

Valency. Univalent. Bivalent. Trivalent. 

Acid HCl H,SO, H,P04 

Salts NaCl CuSO^ NatHPO^, 12H,0 

Base NaOH Ca(OH), Cr(OH), 

A normal solution in water of any chemical is made by taking 
a weight of the pure substance in grams z= "^Q^^^^|^^ weight y ^^^ 
solving it in distilled water and adding distilled water until the 

Digitized by 


290 Marinb and Naval Boilebs 

volume comes up to one liter. If water of crystallization is pres- 
ent in the chemical^ it is included in the molecular weight in 
accordance with its chemical formula. A normal solution of 

HCl contains ^"^^ grams of HCl per liter of solution; one 

of HjSO^ contains ?i^|i^ =49 grams per liter; one of 

Na,HPO„ 13H,0 contains 2x23+1+31+4x16+12(2 + 16)^ 

119.3 grams per liter of solution. 

A normal solution has normal strength when it has the cor- 
rect amoiint of chemical and the chemical and water ingredients are 
pure. The normal solution of any acid will just neutralize the 
hydroxyl in an equal volume of any normal basic solution, and vice 
versa. The normal solution of pure dry calcined sodium carbonate 

(NajCO,) contains ^^^^±^^=63 grams per Uter of solution. 

If the water is not pure (suppose, for instance, it contains some of 
the salts found in sea water), the sodium carbonate will react with 
some of these, decreasing the amount of sodium carbonate, as such, 
in the solution. If the compoimds formed by the carbonate and 
the foreign matter are less dissociated in the solution than the 
pure carbonate, the activity of the solution as a preventer of corro- 
sion is decreased. 

The percentage of normal alkaline strength of any solution of 
a base is measured by neutralizing the alkali in a measured volume 
of it with an acid the percentage of normal strength of which 
is known; the amount of acid used is carefully measured. Sup- 
pose, for instance, it takes 15 cc. of one*-tenth normal acid to 
neutralize the base in 50 cc. of alkaline solution; then the normal 

alkaline strength ^^ gg X ^^ = g^ = j^ , or 3^. The equation may 

be written as foUows: volume of acid used xpercentage 

volume of sample neutralized ^ 

of normal strength of acid used = the percentage of normal alkaline 

strength of the solution from which the sample was taken. 

Digitized by 



Practical Methods of Water Treatment. 

Three methods have been used in the United States Navy to 
prevent corrosion in boilers, viz.: (1) The use of zinc plates, 
specially rolled and metallically connected to the boiler plate, and 
immersed in the water; (2) the use of sodinm carbonate (NajCOj), 
caustic soda and other boiler compounds to keep the water suffi- 
ciently alkaline to prevent all corrosion, or at least to insure that 
only general corrosion may occur; and (3) the exclusion of air 
from boiler feed water by the use of oxygen extractors. 

The use of zincs for boiler protection has been abandoned, as their 
effectiveness was limited. 

'Where boiler compounds or alkalies are used, a good procedure 
is to keep a piece of boiler plate in a sealed jar full of the boiler 
feed water and to note the effect on the test piece from time to time. 
If, then, the alkalinity is sufficient to cause pitting to occur, the 
test piece will indicate the fact. It must be borne in mind, however, 
that the percentage of alkalinity necessary to prevent corrosion de- 
pends upon the quantity of NaCl in the water; and since this 
quantity is subject to wide variations in a short time, there is 
danger that the alkali may become insufficient to prevent corrosion 
due to an increase of NaCl in the feed and that dangerous pitting 
may result. Therefore, the only safe method is to keep the per- 
centage of alkalinity at 0.5^. 

The exclusion of air from the feed water is being satisfactorily 
accomplished by means of oxygen extractors placed on the branch 
feed lines to the boilers in front of the feed stop and check valves. 
If care is used to restrict the access of air to boiler feed corrosion 
wUl be reduced to a minimum. 

Protective coatings of paint on the ship's hull inside and out are 
effective in inhibiting corrosion, but the subject of protective paints 
is beyond the scope of this work. 

Salt water pipes are successfully protected by lead linings, while 
under-water fittings connected to the steel hu^l have zincs attached 
for the protection of steel fittings. Special care should be taken 
to prevent the painting of such zincs when the ship is docked, since 
a coat of paint protects the zinc at the expense of the hull and under- 
water fittings. 

The use of electric currents to prevent corrosion has been suc- 
cessfully used, but has not been adopted by the naval service. This 

Digitized by 


Mabine and Natal Boilebs 

device consists of an insulated electrode immersed in the boiler 
water supplied with a direct current from an independent source. 
The negative lead is taken from the boiler proper. In this manner 
a current is made to flow from the electrode through the water to the 
boiler atid back to the source, causing the electrode to waste away 
and protect the boiler proper. The current must be kept on con- 
tinuously and must be supplied by an independent generator, other- 
wise any heavy grounds in the ship's circuit will stop the current 
through the boiler. If the current is shut off, the corroded particles 
become electro-negative to steel and form a batteiy of which the 
shell is the anode, causing rapid deterioration of the boiler. 

tlhemical Testing Outfit. 

This apparatus is fgr the purpose of ascertaining the quality of 
feed water as regards acidity, neutrality or alkalinity and for finding 
its chlorine content. 

Fig. 105 shows an outfit containing the neceisary equipment for 
making the above determinations, numbered as follows : 

1. Case containing the outfit. 

2. Spring clamp on the door of the case for holding the burette 
when making a test. 

3. White porcelain bowl for holding the sample of water under 

4. Burette secured in place by clamp 2 and ready for use. 

5. Pipette for dropping indicators into sample. 

6. Glass stirring rod. 

7 and 8. Spare burettes. All burette? are graduated to lOO cc. 
in tenths of cubic centimeters ; they have a white back with a verti- 
cal blue line on it by means of which the position of the bottom of 
the meniscus of the liquid can be accurately judged. 

9. Case carrying two B. and W. measuring bottles. Each bottle 
has a zero mark near its bottom. The space between each of the 
graduations holds 5 cc, but the graduations are marked 0, 60, 
100, etc. 

10. Case holding a bottle of red and a bottle of blue litmus 

11. Glass measuring cylinder graduated in cubic centimeters to 
100. (Not shown.) 

Digitized by 


Corrosion and Water Treatment 293 

12. Case holding small beaker for pouring chemicals into burette. 

13. Liter bottle of nitric acid of strength one-half normal. 

14. 500 cc. bottle of anhydrous sodium carbonate or normal 

15. Liter bottle of silver nitrate solution containing 4.101 grams 
of pure silver nitrate in one liter of solution in distilled water. 

16. Bottle of methyl orange solution, consisting of yV gram of 
methyl orange powder dissolved in 1000 cc. of distilled water. 

Fig. 105.— Chemical Testing Outfit 

17. Bottle of potassium chromate indicator of tenth normal 

The principle involved in the tests is the simple chemical volu- 
metric determination of the acid or alkaline strength of the sample 
of water under test, or the number of grains of chlorine per gallon 
contained therein. 

The outfit furnished ships consists of the case and the instruments 
and containers described above, but does not include the chemicals. 
The latter must be obtained upon requisition from the general store- 

Digitized by 


294 Marikb and Naval Boilebs 

keeper at a navy yard^ in sufficient quantities to last for a consider- 
able length of time. 

Indicators. — The determinations are made by the use of indica- 
tors, which give a change of color to the solution when its nature 

Methyl orange solution, when dropped in an acid solution, causes 
it to turn a faint pink. It changes the color of an alkaline solution 
to a pale yellow. 

Blue litmiLS is turned red in an acid solution and is unaffected in 
a neutral or an alkaline solution. 

Red litmiLS is turned blue in an alkaline solution and is unaffected 
in an acid or neutral solution. 

The color reactions of litmus are delayed in water containing 
carbonic acid gas, and are therefore inaccurate in case of such water. 
To obtain accurate color reactions in solutions containing carbonic 
acid gas when using litmus, the solution must be boiling during the 

When running silver nitrate into a solution containing chlorine, 
to which the chromate indicator has been added, a white precipitate 
will be thrown down until all of the chlorine has been precipitated as 
silver chloride. This is due to the fact that the silver in the nitrate 
combines with the chlorine in the water, thus : 

AgNOjH-NaCl=AgCl (white precipitate) +NaN03 (colorless 
in solution). 

2AgN03 + MgCI,=2AgCl+Mg(N03)2. 

When all of the chlorine in the solution has been removed, the 
silver of the nitrate then combines with the chromate of the indi- 
cator, forming a silver chromate solution, which is red, thus : 

K2CrO^H-2AgN08=Ag2Cr04 (red solution) +2KN0, (colorless 
in solution). 

Volumetric Determinations. — In volumetric determinations of 
alkalinity and acidity the percentage of normal strength of the 
alkaline or acid solution is determined. 

A normal solution of any volume of an acid will exactly neutralize 
an equal volume of a normal solution of any alkali or base, and vice 

A liter of a normal solution of any chemical contains the weight 
in grams of the pure chemical obtained by dividing the molecidar 
weight of the chemical formula by its valency. 

Digitized by 



In any compound whose valency is unity, the normal solution con- 
tains the molecular weig^ht of the compoimd in grams in a liter of 
the solution. 

A liter of a normal solution of HCl (hydrochloric acid) contains 
1+36.46=36.46 grams of pure HCl. 

In any compound whose valency is 2 or 3, the normal solu- 
tion contains one-half or one-third, respectively, of its molecular 
weight in grams in a liter of the solution. 

A liter of a normal solution of H2SO4 (sulphuric acid) contains 

2 + 32-f64 98 .« 4^ tt or. 
2^ — = 2 — ^^ grams of HjSO^. 

A liter of a normal solution of HjPO^ (orthophosphoric acid) 
contains ?±?>±^ =.^^ =32.66 grams of H,PO,. 

Method of Using Testing Outfit. 

Alkalinity Test. — Draw a sample of water from the boiler into 
a glass or porcelain receptacle which has just previously been 
washed out with water from the same boiler. 

Fill the burette 4 with acid from bottle 13, using the beaker. 
Open pet-cock at bottom of burette and draw a few drops of acid 
through it into the beaker. Bepeat this if necessary until all air 
bubbles have been expelled from lower end of burette and it is 
filled to tip with acid when cock is closed. 

Measure exactly 50 cc. of the sample of boiler water into the glass 
measuring cylinder, and pour into dish 3, which has just previously 
been washed out with other water from the same sample, or with 
distilled water, and wipe dry. 

Drop 2 drops of the methyl orange solution from bottle 16 into 
the sample in dish 3. If the sample is in the least alkaline, or 
neutral, it will turn a pale yellow when stirred with the glass rod 6. 

Bead the graduation at the top of the acid in the burette ; then 
from pet-cock at the bottom drop acid into the sample in dish 3, 
stirring continuously with the glass rod 6 until sample turns a 
faint pink. Close the pet-cock and read the graduation on the 
burette at the top of the acid. The difference between the two 
readings indicates the number of cc. of acid required to neutralize 
the alkali in the sample: 

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296 Marinb and Naval Boilers 

Each cc. of i normal acid used in neutralizing the alkali in a 
60 cc. sample indicates 1^ of normal alkaline strength. 

Note. — These instructions require acid to be added until the sample 
turns a faint pink. This indicates that the alkali has been a little more 
than neutralized and the sample has become slightly acid. The error, 
however, will be negligible for the purpose of testing boiler water if the 
test is carefully made and the pet-cock is closed at the instant that the 
faintest pink color is attained in the well-stirred sample. For this reason 
the acid should be added drop by drop and the test should be conducted 
in a good light 

Chlorine Test. — The sample in dish 3 is now slightly acid. Be- 
fore testing for chlorine^ the sample must be made neutral or 
slightly alkaline. 

Using pipette 5, drop sodium carbonate solution from bottle 14 
into the sample until it just turns yellow^ indicating that it is 
neutral or slightly alkaline. One drop should be sufficient. 

Eeplace burette 4 with burette 7, and fill 7 with silver nitrate 
solution from bottle 15^ taking precautions as before to see that 
it is filled to the tip. Using pipette 5, drop 4 drops of chromate 
indicator from bottle 17 into sample in dish 3. Bead the graduation 
at the top of the nitrate in the burette; then from pet-cock drop 
nitrate into the sample in dish 3, stirring continuously with the 
glass rod 6, until the sample turns a reddish-yellow color throughout 
Close the pet-cock and read the graduation on the burette at the top 
of the nitrate. The difference between the two readings indicates 
the number of cc. of the nitrate required to precipitate all of the 
chlorine in the sample. 

With this strength of silver nitrate solution, each cc. used in the 
60 cc. sample indicates 1 grain of chlorine in each gallon of boiler 

The stop-cock should be closed as soon as the change in color 
from yellow to reddish-yellow in the well-stirred sample occurs. 
If the nitrate is added until the sample is a deep red^ erroneous 
results will be derived. For this reason the nitrate should be added 
drop by drop after the first sign of reaction occurs, and the test 
should be made in a good light. 

If a light be held under dish 3 while the nitrate is being added, 
the color reaction will be better defined. 

General Instructions. — The percentage of normal alkaline 
strength, Z, of a solution may be expressed thus: 

Digitized by 


CoEKOSiON AND Watkr Tkbatmbnt 297 

where A is the number of cc. of the acid required exactly to neu- 
tralize the alkali in the sample of the solution^ 8 is the nimiber of 
cc. of the sample, and P is the percentage of normal strength of the 
acid used. 

For example, if it is found that exactly 2.2 cc. of a half-normal 
acid are required to neutralize the alkali in a 50 cc. sample of a 
solution, then the percentage of alkaline strength of the solution is 

50 ^ 2 100 ' 

or the solution is 2.2$^ of normal alkaline strength. 

From the above equation it may be seen that any variation from 
the prescribed size of sample tested, or any variation from the pre- 
scribed strength of acid used, will directly aflfect the accuracy of 
the determination of the alkaline strength. Every care must be 
exercised in compoimding the reagents and in making the titrations. 

To provide reagents of standard known strength, there is kept 
in store at all naval stations, and obtainable on requisition, a supply 
of the chemicals properly mixed for use solely with this outfit. 

To compoimd an acid solution of half-normal strength, exactly 
32 cc. of standard acid (between 69^ and 70j< pure acid by weight) 
should be mixed with 968 cc. of distilled water. Bottle 13 is sup- 
posed to be of 1000 cc. capacity, but commercial bottles vary in size. 
If the 1000 cc. level is once accurately determined by use of the 
burette, and marked with a file scratch, the solution can be easily 
compounded whenever necessary by running 32 cc. of the acid from 
a burette into the bottle and adding water up to this 1000 cc. mark. 

If for any reason the standard acid referred to above is not avail- 
able, a solution may be prepared by using any acid not containing 
chlorine (though nitric acid is to be preferred), as follows: 

Make up a solution by mixing with distilled water enough of the 
acid, according to what its strength is known or supposed to be, to 
make approximately a half-normal solution, and then proceed to 
determine the exact strength of the solution, thus: 

Measure exactly 50 cc. of the acid solution in cylinder 11 and 
pour into dish 3. Add 2 drops of the indicator from bottle 16 
and stir with the glass rod. The sample will turn pink. Fill burette 
8 to the tip with normal sodium carbonate solution from bottle 14, 
and read the height of the solution in the burette. Kun sodium 
carbonate solution into the sample, stirring continuously, and close 
the pet-cock at the instant that the sample changes color from 

Digitized by 


298 Mabikb and Naval Boilbrs 

pink to yellow, indicating that the aoid has been neutralized. Read 
the height of the solution in the burette and determine how many 
cc. of the sodium carbonate solution have been used. 

Remembering that a given quantity of an alkaline solution of 
a given strength will exactly neutralize the same quantity of an 
acid solution of the same strength, that the sodium carbonate solu- 
tion is of normal strength, and that the sample of acid solution 
contains 50 cc, it is apparent that if it required, say. 20 cc. of the 
sodium carbonate solution to neutralize the acid, then the acid 
strength of the sample is |^, or f of normal acid strength. 

Suppose that, in testing a sample of boiler water in the manner 
heretofore described, it is foimd that 3 cc. of this f normal acid is 
required to neutralize the alkali in the 60 cc. sample; then, employ- 

ing the equation Z= o xP, the alkaline strength of the sample 

is ^ X I = .024 ; in other words, the boiler water is 2.4^ of normal 
alkaline strength. 

If the water is very muddy in appearance, it will be found advis- 
able to allow the samples to stand in their original containers, 
before making the test, imtil the sediment in the water has settled. 

The chlorine test depends upon the fact that, when any volume 
of solution containing 4.101 grams of silver nitrate per liter is just 
sufficient to precipitate all the chlorine in an equal volume of a 
sample, the sample contains 50 grains of chlorine to the gallon of 
231 cubic inches. Hence, the chlorine content of a sample may be 
expressed thus : 

Z=-J X50, 

where X equals the grains of chlorine per gallon of sample, 8 equals 
cc. of original sample tested, and "S equals cc. of nitrate of silver 
solution of 4.101 grams per liter required to just precipitate all the 
chlorine in the aample. 

Note. — The sample in dish 3 at the beginning of the chlorine test 
consisted of more than 50 cc. of total contents, being made up of the 
original 50 cc. of boiler water, and the amounts of indicators, acid, and 
alkali added subsequently. However, the reaction for determination of 
chlorine depends upon the precipitation of all chlorine contained in 
dish '^: and since none has been either added or subtracted by the ad- 
dition of the other reagents, the amount of nitrate of silver required to 
precipitate all the chlorine in the augmented sample is a direct measure 
of the chlorine content in the original sample of 60 cc. expressed in 
terms of grains per gallon. 

Digitized by 


Corrosion and Water Treatment 299 

The test for chlorine as described above will determine the chlorine 
content within a fraction of a grain, and should be employed when 
testing water from condensers, distillers, and feed tanks, and 
generally any water known or supposed to contain less than 50 
grains of chlorine to the gallon. 

For the rough determination of high chlorine content, the grad- 
uated measuring bottles may be used as follows : Having made the 
sample neutral or very slightly alkaline, after the test for alkali, 
decant into the graduated measuring bottle until the top of the 
sample is level with the graduation marked 0. The tube now con- 
tains 5 cc. of the sample. Add one drop of the chromate indicator 
from bottle 17; slowly add silver nitrate solution from bottle 15; 
keep shaking the tube. On nearing the full amount of nitrate 
solution required, the sample will become reddish for an instant, 
but wiU turn back to yellow when shaken. Add nitrate solution 
drop by drop, and as soon as the sample shows a reddish yellow and 
remains that color when shaken, stop adding nitrate. . The reading 
of the graduated tube at the top of the sample will show the grains 
of chlorine per gallon. This is because the graduations, beginning 
from the bottom of the tube, are in increments of 6 cc, and a given 
volume of a nitrate of silver solution containing 4.101 grams to the 
liter will just precipitate all of the chlorine in an equal volume of 
water containing chlorine in the proportion of 50 grains to the 
gallon. It follows that double the amount of nitrate solution will be 
required to cause the same reaction in water containing chlorine 
in the proportion of 100 grains to the gallon, etc. 

Note. — (a) The fact that one or more reagents must be added to the 
sample before the silver nitrate solution Is added, and the proportional 
Yolomes he thereby disturbed, vitiates somewhat the accuracy of the 
results of this method of test But as the method Is necessarily a rough 
one at best, the error Introduced by adding the reagents will be negligible 
unless a relatively large quantity of acid or alkali has been required to 
make the sample nearly neutral. 

(b) Using this method, chlorine up to about 900 grains per gallon may 
be measured. If the sample contains more than this, proceed as follows: 
Take 10 cc. of the sample and dilute with 90 cc. of distilled water. Take 
6 cc. of the diluted sample and proceed as before. Each 5 cc of silyer 
nitrate added now Indicates 500 grains of chlorine to the gallon. Other 
proportions may be used In a similar manner. 

It is important that before collecting samples of water from 
boilers^ tanks^ distillers, etc., the receptacle in which the sample is 
collected be well rinsed out with distilled water or water from the 

Digitized by 


300 Marinb and Naval BomEBii 

same boiler^ tank^ or distiller which is to be sampled. Otherwise 
precipitates from a previous sample may remain in the receptacle 
and be redissolved^ and the test will give erroneous results. Simi- 
larly the dish 3 should be thoroughly washed and dried after each 
testy to remove traces of previous sample and of the reagents used 
in testing it; and^ generally, before using burettes, beaker, measur- 
ing cylinder/ etc., with any sample or reagent other than the same 
with which they were last used, they should be well rinsed out with 
a quantity of the liquid with whicl^ they are about to be used. 

The litmus papers are furnished for rough qualitative alkaline 
or acid determinations. They should be used with caution. When 
used with water or any other liquid having an aflSnity for CO,, the 
liquid should be boiling, since the presence of CO, will cause the 
color reaction to lag and results may be very misleading. 

The subject of ferroxyl-mounts (corrosion indicators) is taken 
up in the Appendix. 

Digitized by 



The United States Naval Instructions lay down certain specific 
instructions for the care^ preservation and management of boilers 
and machinery. These instructions embody the results of experi- 
ence and good practice up to the time they were written. More 
extended experience^ alteration of design, and military expediency 
necessitate occasional changes in them. 

The essential considerations are: (1) Safety, (2) reliabUiiy, 
(3) prevention of deterioration, (4) economy. 

Knowledge of engineering and of engineering materials in gen- 
eral is essential, and a thorough understanding of every detail of 
the particular plant is necessary for its proper care and management. 

Boutine. — ^A definite routine of work, inspections and reports 
prevents omissions, delays and friction among the personnel. The 
Begulations and Instructions should be gone over thoroughly, and . 
specific times should be designated for carrying out their require- 

Special Instructions. — Certain special features of the boiler man- 
agement and machinery operation in the fire-rooms, as well as the 
necessity for training the fire-room force, will require the posting of 
special orders and instructions for the guidance of all concerned. 

"Erequent" and "Eegular" Intervals. — The repeated recur- 
rence of the words " frequent *' and " regular " in reference to the 
examination, overhauling and testing of tiie machinery is indicative 
of the necessity for careful periodic examinations, to prevent faults 
developing or to enable small defects to be discovered before they 
develop into serious defects. 

The particulars outlined below cover many points which arise 
in the management of the boiler plant. 

Damage from Freezing. — ^Water in boilers and other vessels 
should not be allowed to freeze in cold weather. Particular care 
in this respect should be exercised with steam-laimch boilers and 
water jackets of gasoline engines. Damage from freezing fre- 
quently occurs, as the result of a fall in temperature during the 
night after machinery is secured. 

Digitized by 


302 Marine and Naval Boilbbs 

Loss by Leakage. — ^The loss of water due to leaky valves, joints, 
drains, glands, and jackets would, in many cases, be surprising if 
calculated. Besides the direct loss of fresh water, there is also, in 
many cases, a loss from deterioration due to rust formed in the 
vicinity of the leaks. 

Air leaks lower or destroy the vacuum in condensers. Air get- 
ting into the feed water through the drains or from any otiier 
source is the most potent factor in the internal deterioration of 

Salt Water in the Feed System. — Salt water may get into the 
feed system in the following ways : 

(1) Through leaky condenser (main or auxiliary). 

(2) Through evaporator drains. 

(3) Through leaky reserve feed tank (manhole gasket or leaky 

(4) Through salty water in ship^s tanks. 
(6) Through bottom blow pipe. 

(6) Through evaporator vapor to auxiliary exhaust (where 

(7) Through pumps having connections to drainage system and 
feed system (where fitted). 

(8) Through drains from steam-heated salt-water baths. 

The harmful effects of salt water necessitate stringent precau- 
tionary measures to prevent its introduction into boilers. 

Preservation of Idle Boilers. — Boilers, when not under steam nor 
open for cleaning, overhauling or exammatiou must be kept quite 
full of fresh water made sufficiently alkaline to prevent pitting. 
They must be pumped full within 24 hours of the completion of 
steaming, and must be so kept imtil within 24 hours of again 
raising steam. 

Whenever, for a particular reason, it is not practicable to keep 
idle boilers full of fresh water, the following alternate method 
must be used for their internal preservation : They must be emptied 
and their interiors must be dried out as thoroughly as possible. 
Open trays, of as large capacity as practicable, and filled to about 
half their height with quicklime, must be introduced through the 
manholes into the upper and lower parts of each boiler. They must 
then be closed air-tight, and special precautions must be taken to 
prevent any moisture from entering the interiors while they are 
being thus treated. If necessary, joints of the feed and blow systems 

Digitized by 


Gabb and Managbmbnt of Boilers 303 

must be broken and adjacent sections of steam piping must be shut 
off and their drains be left open. 

Whenever the boilers are open for cleaning and overhauling, 
their interiors must not be allowed to remain in a damp condition 
longer than required to accomplish the necessary cleaning. The 
cleaning and washing out of the interiors must be completed as 
soon as possible after openings and then the boilers must be closed 
at once and filled. If, to complete repairs or overhauling of the 
internal fittings, it is necessary to keep the boilers open for a con- 
siderable time after they have been washed out, their interiors must 
be thoroughly dried out and kept dry until they can be closed and 

To prevent corrosion while exposed to the atmosphere, espe- 
ciaUy during periods of wet weather, the fire sides of the tubes and 
other heating surfaces, fittings, and parts within the furnaces, com- 
bustion spaces and uptakes of idle boilers must be kept free from 
moisture. Light fires in small stoves or pans placed in the furnaces 
or ash pits may be used to dry out empty or idle boilers. 

The furnace and ash-pit doors, and the dampers in the up- 
takes, of all idle boilers must be kept closed. The furnaces of 
empty boilers must not be primed. When practicable, the funnels 
and escape pipes must be kept covered when all of the boilers con- 
necting to them are idle. 

Precautions when Overhauling Boilers. — ^To prevent accidental 
scalding of men working inside boilers, all connections through 
which steam or hot water might enter the boiler must be lashed shut 
before men are allowed to enter them. 

In opening boilers after they have been steaming, the air cock 
should be opened first to relieve any pressure which might not be 
shown by the pressure gage. The boiler should be thoroughly 
ventilated, and the air should be tested with a lighted taper or 
candle, before anyone enters. 

Danger from Scale and Deposits. — Scale on the water surfaces 
of boilers forms a non-conducting layer and reduces evaporative 
efficiency. If the scale is thick enough, the intense heat on the fire 
side will raise the temperature of the metal high enough to weaken 
it so that it may rupture under the pressure of the steam. Salt, 
oil, mud and vegetable and animal matter in the water cause scale. 
Besides scale, grease also causes priming, because it spreads over the 
surface of the water and resists the escape of steam bubbles through 

Digitized by 


304 Marine and Naval Boilsbs 

the surface. The steam collects in spots and bursts through the oil 
film, carrying the water with it. Vegetable and animal matter also 
disintegrate and form acids which increase the electrolytic action 
of the water and hasten corrosion. 

The sources of salt in feed water have been mentioned. Muddy 
and impure water may come from barges or navy yards. Oil gets 
intd the feed water through drains from engines operating with a 

Boiler water should be pure. Whenever it is necessary to obtain 
water from shore or from barges, it should be tested, and should 
not be accepted if impure. Military necessity or other circumstances 
may, at times, make the use of impure water necessary. In such 
case, additional caution should be exercised to prevent deterioration. 

Changing the Water. — Water in boilers should be changed only 
when impure, salty or dirty. A boiler on a large battleship 
contains from nine to eleven or more tons of water, and its loss is a 
considerable item. Using boilers to trim ship, or as reserve feed 
tanks, necessitates the shifting of the water level and the introduc- 
tion of air into the boiler, increasing corrosion, particularly at the 
water level. The boilers are installed to generate steam and for that 
purpose only. They must not be used for any other purpose except 
in case of urgent necessity. 

Semoval of Impurities. — All devices fitted for the removal of 
air and impurities in feed water should be kept in constant use. 
Grease extractors should not be bypassed when dirty, but should be 
cleaned and the toweling should be shifted as often as necessary. 
Loof a in feed tanks should be cleaned or removed when dirty. Air 
and water leaks should be sought and remedied daily. 

Test of Water. — The water in all boilers under steam must be 
tested daily for alkalinity and salinity, using the standard navy 
boiler water-testing outfit. The water in the feed tanks must be 
tested every watch. A routine of supplying alkali to the feed water 
should be established in order that the prescribed degree of alkalinity 
may be maintained. 

The corrosive properties of the boiler water may, to some extent, 
be determined by placing a piece of clean steel of the same compo- 
sition as that of the boiler in a sample of boiler water in a bottle 
for at least 24 hours. Any especially harmful ingredients will cause 
rust spots to form on the steel in less than 24t hours. 

Digitized by 


Cabb and Management of Boilebs 305 

Water Treatment. — It has been Bhown that boiler water must be 
kept alkaline in order to reduce corrosion. The alkalinity must be 
maintained at that prescribed by the Bureau of Steam Engineering. 
The alkali may be put into the boiler by means of a short reducing 
coupling on the suction of an auxiliary feed pump, or it may be put 
into the feed tanks. If lime is used, it must be dissolved in cold 
pure water, and the precipitated residue must be thrown away. 
Only the water of the solution is used. After boilers have been 
overhauled, the alkali may best be put into the boiler direct, through 
manholes or handholes. When water has remained in a boiler a few 
weeks, the alkali settles to the lower parts and the water will show 
a lower percentage of normal alkaline solution than actually elists 
in the boiler. The water should be circulated by means of an 
auxiliary feed pump to stir up the alkali before the weekly test is 

Periodical Cleaning. — Boilers should be examined and, if neces- 
sary, cleaned and overhauled at regular intervals. The type of 
boiler, conditions of service, locality in which the ship has remained, 
age of the boiler, and many other special circumstances will deter- 
mine the frequency of such cleaning and overhauling. The engineer 
officer is responsible for the condition of the boilers, and is the judge 
as to the advisability of overhauling them. Under average con- 
ditions, the interval should be about 700 hours of steaming. Fire 
sides are cleaned as practicable while steaming, as by blowing 
tubes, etc. 

Cleaning Eoutine. — Whenever a boiler is laid up for overhauling, 
a routine of cleaning should be followed. The routine must be such 
as to include every part of the boiler. A good procedure in over- 
hauling the boilers is as follows ; 

(a) Clean fire sides and everhaul all furnace fittings, brick-work, 
baffling and fire parts. 

(b) Empty, open and wash out the water spaces with fire hose. 

(c) Clean and inspect the water side and internal fittings. 

(d) Binse out with fresh water and close the boiler. 

(e) Overhaul all valves, gages, cocks and other external fittings 
as rapidly as possible ; then fill boiler with alkaline fresh water. 

(f ) Examine and repair, as required, all parts of the lagging, 
casing and seating. 

(g) Apply water-pressure test for tightness of valves, gaskets, etc. 

Digitized by 


306 Marine and Naval Boilers 

(h) Test for tightness under steam, including tightness of 

(i) Adjust safety-valves. 

Ashes and soot should be removed from the furnaces as soon as 
practicable after the fires are allowed to die out. If they are 
allowed to remain long in the ash pans, or on furnace floors, and 
against boiler casings, moisture may get into them and cause 

Water should not be used in the ash pans except when absolutely 
necessary to prevent warping and to prevent the formation of 
clinkers. The lower parts of boilers, such as the seatings, lower 
drums and lower parts of the casing, need particular attention to 
prevent corrosion. 

Scale on the outside of the tubes is best removed while the boiler 
Is hot, by using an air blast or steam blast to dislodge it. If 
allowed to remain until the boiler is cold, it may come oflE with 

A hot steam blast should in no case be directed against cold tubes 
of boilers. 

Examination of Tubes. — ^Boiler tubes should be examined fre- 
quently on the fire side. The tubes next to the furnace space are 
most liable to bulge and warp. Fouling, both internal and external, 
causes imequal heating, with consequent unequal stresses resulting 
in distortion. Distorted tubes should be examined and, if bulged 
or blistered considerably, should be removed. 

Securing Tubes. — All tubes of water-tube boilers, except Field 
tubes, should be flared at the ends to prevent their pulling out of 
the tube plates or headers. The tubes must extend through the 
plates into which they are expanded about VV"> ^^d the flaring 
should be materially greater than the hole into which the tube is 

Particular attention should be paid to tubes in boilers of the 
bent-tube type, because these tubes under pressure tend to pull out 
of the tube plates. Tubes so badly worn at the ends that the bevel 
is worn down to the plate should be renewed. In renewing tubes, 
it is necessary that the hole for the tube be bored smooth and 
cylindrical, and that the edges be rounded slightly to give a good 
holding surface and to prevent cutting of the tube. The tube must 
be expanded evenly into the tube hole. 

Digitized by 


Garb and Manaqbment of Boilebs 307 

Protection of External Farts. — The external parts of the boilers, 
such as the tops, uptake casings and back casings, are the most in- 
accessible and most easily neglected, though they frequently need 
most attention. Water dripping from drains, sweating of pipe 
lines, and salt water from hoses, splashed on the casing result in 
corrosion. Paper and. trash accumulate quickly on the tops of 
boilers and in the bilges back of them, unless due vigilance is exer- 
cised to prevent their accumulation. The tendency of the fire- 
room force to stow tools and gear back of boilers should be dis- 
couraged. All gear, spare parts, etc., necessary to be stowed in the 
fire-rooms should be in boxes on the bulkheads. When ashes have to 
be stowed in the fire-rooms, canvas or boards should be used to 
prevent the ashes from getting against the boiler casings and bulk- 

The smoke-pipe guys must be adjusted with change of tempera- 
ture, and their turn-buckles must be kept' oiled. 

Fire-Koom Gratings. — The gratings over the fire-room hatches 
must not be taken off except in case of necessity, and should then be 
replaced as soon as possible. Material which would obstruct the 
ventilation, or fall through the gratings and injure the machinery 
or personnel below, must not be stowed on the gratings. 

Becord of Examinations. — When the boilers and machinery are 
examined, a careful record of their condition should be kept in a 
book and the general condition entered in the steam log. A great 
deal of trouble, extra work and extra expenditure of time are 
caused by the lack of a proper record of the performances, repairs 
and overhauling of boilers and machinery. The records are par- 
ticularly helpful when a change in detail of engineer officers occurs. 
Reports of imusual cases of damage and deterioration, and of any 
occurrences of particular or unusual interest, should be made to the 
Bureau of Steam Engineering. Such reports promote improve- 

Safety-Valves. — ^The designed load on the safety-valves, that is, 
the designed steam pressure per square ilich at which the safety- 
valves are set to lift when the boiler is newly built and installed, 
may have to be reduced on account of deterioration of the boiler 
due to special causes or to length of service. The frequent examina- 
tions, periodical overhauling, and special tests will determine the 
extent of the reduction necessary. The TJ. S. Naval Instructions 
fi^ive a definite procedure in the case of worn boilers. 

Digitized by 


308 Mahinb and Natal Boilebs 

The hand lifting gear must I)e tested weekly to make sure that 
the valves do not become frozen on their seats; and when the 
boilers are under steam, the valves must be lifted weekly by steam. 
When raising steam in a boiler, its safety-valve must be lifted by 
steam and, if necessary, adjusted to lift at prescribed pressure before 
the boiler is connected. If, for any reason, the safety-valves do not 
lift and reseat properly, they must be put in proper working order 
without delay. In setting the valves, the three usually installed 
should be set so that the lifting pressures vary by a poimd or so. If 
all lifted at once, it would be difficult to tell from the sound that all 
had lifted. It is, however, usually unnecessary to attempt such re- 
finements, as it is rather difficult to set all the valves to lift at exactly 
the same pressure, so that there will usually be the necessary dif- 

Pressure-gages fitted on boiler fronts are frequently deranged 
by the heat and give false readings ; therefore, when testing safety- 
valves, it is necessary that the Senior Engineer Officer assure him- 
self that the readings of the pressure-gages are correct. 

The spare springs of safety-valves should be kept dry in the 
boxes in which they are stowed, and should be oiled if necessary, to 
keep them from rusting. 

Water-Oage Fittings. — Particular care should be given all water- 
gage fittings. The glasses should be blown through by the water 
tender of every watch coming on, to make sure that the water com- 
mimicates through the pipes. Gage cocks must be tested every 
watch when steaming. Sometimes there is a tendency among the 
fire-room force to dispense with the routine tests because they start 
leaks. The whole theory of tests is that leaks and faults may b& 
discovered in time to prevent deterioration and breakdown. 

Oage Tests. — ^Boiler steam-gages should be tested at least once 
every three months, and corrected by comparison with a standard 
gage or by adjustment with the gage-testing outfit. Vibration, 
heat, or accidental striking of the gages may introduce errors in 
their readings. The dial pointer is usually secured to its spindle 
with a friction fit, and may jar loose. Gages placed on boiler 
fronts are particularly subject to derangement due to the heat. 

Tests of Pressure Parts — ^Wom Boilers. — The pressure parts of 
worn boilers, except the tubes, are best tested by drilling holes about 
i" in diameter through the worn parts and measuring the thickness. 
The holes should be plugged with screw plugs riveted over. The 
extent of the wearing, such as that due to pitting, can only be 

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Carb and Management of Boilers 309 

guessed at by eye. If there is any suspicion as to the thickness of the 
part^ the drill test should be made. A careful record of the location 
of the parts tested^ of the original thickness and that after test^ 
together with any special facts of interest in regard to the tests, 
must be entered in the boiler record and the steam log. Drill tests 
must be carried out in strict accordance with the Naval Instructions. 

Water-Pressure Test. — After general overhauling, or when the 
boiler has been out of service for a long time, or if, for any reason, 
a boiler is considered to be weak, a water-pressure test is given the 
boiler to determine its tightness and the strength of its material. 
In the U. S. Navy the following is the prescribed procedure : 

N. I. 3076. (1) The boiler shall be tested by water pressure at 
such times as the engineer officer may deem necessary or advisable. 

(2) Whenever such test is made to prove the safe strength or the 
tightness of any riveted, expanded, or other permanent structural 
joints or parts of a boiler, the following method shall be employed : 
The water shall be heated to a temperature of not less than 150** P. ; 
and, before applying pressure, the boiler shall be completely filled 
with water and entirely free from air, and necessary precautions 
shall be taken to insure that there be no leak past the main or 
auxiliary stop valves into pipes that may contain steam. The pres- 
sure to be applied shall not exceed one and one-quarter times the 
authorized safety-valve setting unless special directions from the 
Navy Department, commander-in-chief, or senior officer present are 
received. For ordinary overhaul of boilers, referred to in Article 
3065, Naval Instructions, the hydrostatic pressure described and out- 
lined in *^ Instructions for care, preservation, and operation of boil- 
ers *' will be used, as it is not advisable to subject boilers to imneces- 
sary strains except for special reasons. In the case of fire-tube 
boilers that have been in service longer than two years, the water 
pressure to be applied shall be limited to 25 per cent greater than the 
load on the safety-valves. The pressure shall be increased slowly 
and be very carefujly applied, in order that injury may not be caused 
by over-pressure, particularly if a drill test should have revealed 
unusual thinness of any parts. 

(3) During the application of the water pressure, the boilers 
shall be carefully examined and proper gages be used, when prac- 
ticable, to detect any change in form in any of their parts. Shoxdd 
any indication of probably permanent deformation be observed, the 
fcest shall cease, and the weak parts shall be strengthened as neces- 
sary. If this be not practicable, a new test pressure 20 pounds 

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810 Marine axd Naval Boilers 

below that at wliich pennanent deformation commenced shall be 
adopted, and the new working pressure shall be that which corre- 
sponds to such new test pressure, according to paragraph (2). The 
load on the safety-valve shall be reduced to the new working 

N. I. 3077. To prove the tightness of all valves, gaskets, and fit- 
tings of boilers under the working pressure, the following tests will 
be made, if practicable, upon the completion of each general over- 
hauling or repair affecting such parts. A water pressure of 10 
pounds per square inch less than the load on the safety-valve shall 
be applied. After attaining this pressure, all connections, includ- 
ing the feed, stop, and check valve, shall be closed and the dropping 
pressure during a considerable number of hours be noted. If the 
test be made with water of nearly the same temperature as the 
boiler and the fire-room, the dropping pressure should not exceed 
20 pounds in 24 hours. If there be no leaks in the boiler or its 
fittings, there will be no change in the boiler pressure other than 
that due to change in temperature of the boiler or the water, or 
both. It should be borne in mind that leaky feed valves will give 
false indications, and that, until gaskets are softened by heat, there 
may be slight leaks around the plates, which will readily take up 
under steam pressure. For the latter reason, whenever sufficient 
time is available, this test should be made after steam has been 
raised to adjust the safety-valve and the boiler has again cooled 
down, when this is done in connection with general overhauling. 
Although hot water searches out leaks with more facility than cold 
water, the time element included in this test affords opportunity 
for the water to cool, with consequent contraction in volume and 
reduction in pressure, giving an appearance of leaks which may not 
exist. For this reason water used for this test should be as nearly 
as possible the temperature of the boiler and of the fire-room. 

Precautions in Begaid to Fuel Oil. — ^The advent of oil as a fuel 
for boilers has necessitated certain precautions not required with 
coal. The precautions place restrictions particularly upon (1) 
smohing, and (2) open (naked) lights. 

The principal source of danger with fuel oil is the explosive vapor 
which it gives off. This vapor is heavier than air and accumulates 
in low pockets and bilges. In general, no spark from any source, 
as from smoking, open lights, etc., must be allowed to get into any 
compartment where fuel oil is stowed or used. Also, all pipes, tanks 

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Cabe and Manaobment of Boilers 311 

and compartments which have contained fuel oil must be freed from 
possible accumulations of explosive vapor by steam, water or air 
blast before anyone is allowed to enter or work on those containers. 

Especial care is needed to prevent the accumulation of oil in the 
fire-room bilges and on the fire-room floors. If the oil is accidentally 
spilt, it must be wiped up immediately. 

No smoking, nor any naked lights, should be allowed near the fuel 
oil tanks and vents or near the hose through which oil is being taken 
on board. 

The electric fuzes in circuits in compartments where oil is used 
must be of the enclosed type, and electric lamps must have some type 
of protective covering aroimd the bulb. 

Oil-burning boilers are not now fitted with dampers; but in 
vessels using both oil and coal, and in oil-burning boilers which 
have dampers, such dampers must always be wide open when the 
boiler is under steam. 

Steam-launch Boilers. — Steam-launch boilers are subject to a 
great deal of wear and tear incident to service, and should be ex- 
amined frequently both inside and out and repaired as necessary. 
Particular attention should be given the internal feed pipe, dry pipe, 
safety-valves, water-gages, and other fittings. If, in emergency 
or other unavoidable circumstance, salt water is used in launclr 
boilers, they should, as soon as practicable after such use, be 
thoroughly cleaned and scaled on the inside. Laimch boilers con- 
tain a comparatively small amoimt of water, and any deposit from 
salt water collects more quickly and causes more rapid overheating 
and consequent distortion than in boilers containing a greater 
relative quantity of water. If the boiler is of the Ward drop-tube 
type, scale is especially harmful, as it collects in the bottoms of the 
drop tubes and in a short time causes rupture from overheating. 

Draining of Water Containers. — All pipes and cyliiltlers, for 
either water or steam, and all condensers and other water containers, 
must, when not in use, be well drained. Water remaining in them 
may cause rusting in the containers themselves, or may leak and 
cause rusting in the vicinity of the leak outside the container. A 
more probable and more serious danger is that from water-hammer 
when steam or water is again turned into the piping. 

Equalization of the Work of Boilers. — A record is kept of the 
number of hours under steam of every boiler, from the date of com- 
mission of the ship. From this record it is possible to equalize the 

Digitized by 


312 Mabinb and Naval Boilers 

work among the boilers and thus obtain for each the same average 

Increasing Speed with Fire-Tiibe Boilers. — Cylindrical fire-tobe 
boilers^ on account of their construction, will not stand the unequal 
contraction and expansion and wear on the metal when the boiler 
is forced at a rate much above that of natural draft. Leaks result; 
so that, when it is necessary to increase speed, additional boilers 
should be used. Here, as in many cases of emergency or military 
necessity, a rule cannot be strictly followed, but the results of 
forcing should be understood, and increased vigilance should be 
exercised, should the necessity for forced draft arise. 

Training of Firemen. — In order that the best results may be ob- 
tained when the development of the highest power is a matter of 
great importance, frequent opportunity should be given for training 
the firemen to work the boilers at their fidl capacity imder both 
natural and forced draft conditions. With this object in view, and 
to insure that the boilers in use are being worked at approximately 
their full capacity, when more careful firing will be necessary than is 
required imder easier or more economical conditions of steaming, no 
more boilers must be employed upon such occasion than are required 
for the speed ordered. 

Particular attention must be given to the training of the fire- 
men, especially as regards the management of the fires, and all 
engineer officers and fire-room petty officers must take advantage of 
every opportunity to instruct the firemen how to bum the fuel in 
the most economical manner. Every effort must be made to keep 
the steam pressure and the water level in the boilers constant, to 
work the fires in the most efficient and systematic manner, and to 
use to the best advantage all appliances that may be fitted for tim- 
ing the operations of firing, for regulating the supply of air, and for 
economizing in any way the expenditure of fuel. The engineer 
officer must ascertain the most economical rate of consumption of 
fuel, together with the number of boilers it may be necessary to 
employ, for any required speed and condition of steaming. 

A time firing device is a very efficient means of obtaining uni- 
formity in the firing interval. 

When burning coal, careful attention must be given to the 
management of the fires, to secure the utmost economy and efficiency 
of combustion. The fires must be maintained at a imiform thick- 
ness in all parts of the furnace; this should be about S" thick for 

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Gabe and Management of Boilers 313 

natural draft, and from 10" to 12" for forced draft. Green coal 
should be added to the fire at regular and frequent intervals, and 
should be scattered over the entire surface. An excellent scheme 
for training new firemen to distribute the coal evenly over the grate 
is to lay out a space equal to the grate area on the fire-room floor 
and have them practice shoveling the coal over this model grate. 
After a little practice, great proficiency is obtained, as the fireman 
can easily see where he has failed to cover the space properly. 

The furnace doors should be kept open only the shortest possible 
time. Holes in the fire or the accumulation of clinkers in any part 
of the furnace must be prevented. All lump coal must be broken 
up before being fired. The fires should be cleaned at regular and 
frequent intervals, and as often as necessary to keep them in good 
condition. Care must be taken to remove all clinkers alhering to 
the grate bars. The necessary cleaning should be done as quickly as 
possible in order to reduce to a minimum the amount of cold air 
admitted through the uncovered grate and the furnace door. The 
uptake dampers should be closed while cleaning fires. The uptake 
dampers, rather than the ash-pit doors, should be dosed when 
necessary to temporarily check the rate of combustion ; the closing 
of the ash-pit doors is liable to cause the burning or buckling of 
the bearer bars and grate bars. The use of water in the ash pans is 
unnecessary under ordinary conditions, and should not be re^^ortod 
to except when necessary to prevent clogging of the grates by exces- 
sive clinkers. It sluyidd he ihorougMy impressed upon all the fire- 
room force that the primary object of the damper is to check the 
draft and control the output of steam and that it should always he 
used for that purpose. Any other means of controlling the steam 
pressure except the starting of additional aucciliary machinery or 
the lifting of the safety-valves may result in harm to the boiler. 

Unequal Expansion. — Probably the most important point in (con- 
nection with the operation of boilers, 3^et the one most often for- 
gotten, is the harmful effect of unequal expansion and contraction, 
due to difference of temperature, upon the strength and life of the 
boiler. The excessive strains taking place in metals and materials 
on account of local variation of temperature are of such common 
occurrence in metallurgy and every-day life as to need no com- 
ment. In spite of all precautions to prevent unequal contraction 
and expansion while the boilers are in operation,, their entire 
prevention is impossible. The desirability of reducing their harm- 

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814 Mabine and Nayal Boilbrs 

ful effects to a minimum should be apparent. The less rigid the 
construction of the boiler^ the less is it affected by varying t^npera- 
tures. Hence^ Scotch boilers require more time m which to generate 
steam than do water-tube boilers. Experience shows that about 
eight or ten hours is desirable when raising steam in Scotch boilers^ 
while about two hours is a good rule for water-tube boilers. If 
brick- work is new, more time is necessary to dry out the mortar and 
cement. Holes in the fires, especially at the front of the grate 
between doors, frequently cause great strains and leaky nipples (in 
B. and W. boilers) over them. 

Precautions in Eaising Steam. — ^Before starting fires in any 
boiler, all valves and other fittings such as drain cocks, bottom and 
surface blow valves, handhole and manhole plates not intended to 
remain open, must be examined to see that they are tightly closed. 
The safety-valves, boiler stop valves, feed check and stop valves and 
water-colunm gage and test cocks must be tested, to see that they 
are all in proper working order. It must be made certain that the 
valves and pipes leading to the pressure-gages and water-gages 
are wide open. The water shall be brought to a height that is slightly 
below the normal steaming level. The air cock must remain open 
while the water is being run down and while steam is being raised, 
and must be closed after steam has formed. 

While steam is being raised in a boiler, close attention must 
be given to all the boiler fittings and feed arrangeinents, to in- 
sure that thej are in all respects in proper working order. Special 
care must be taken, in setting up the nuts of handhole and manhole 
fittings, that no greater leverage is applied than the proper spanner 
provided for that purpose. Ash-pit doors of automatic or balanced 
type must always be left mounted while boilers are under steam. 
The boilers should be connected to the steam line when there is a 
difference of pressure not exceeding 10 pounds, and the boiler stop 
valve should at first be only slightly opened, to allow the pressures 
in the steam line and in the boiler to equalize gradually. After 
the pressures have equalized, the stop valve may be further opened 
gradually to such extent as required. 

Whenever steam is raised in a boiler, in order to insure that 
the safety-valves are in good working order and to ascertain the 
exact pressure at which they will lift, the steam pressure must be 
allowed to rise until these valves should lift if properly adjusted. 
This may be done after the boiler has been connected, if more con- 

Digitized by 


Cabb and Managbmbnt of Boilbbs 316 

venienty but the boiler must not be continued in use unless the 
safety-valves have been correctly adjusted. 

The safety-valves are adjusted by trial and error by netting up 
or easing oft on the compression nut or running the hudiling ring 
up or down as necessary to increase or decrease the lifting and re- 
seating pressure. If the pressure is seen to go appreciably higher 
than that at which it is desired the valves should lift^ the damper 
is closed and the safety-valve is lifted by the hand gear^ ir case the 
pressure cannot be checked by means of the damper. When the 
valve lifts^ the pressure drops until the valve reseats. To lift the 
valve again^ the damper is opened and the pressure rises. Each 
time the valve lifts^ the pressure is noted and slight changes are 
made in the adjustments. When one valve of the set is regulated 
as closely as possible to the load desired^ it is gagged and tho others 
of the set are adjusted in a similar manner. 

Feed- Water Heaters. — The temperature of the feed watei enter- 
ing the boiler should be kept as high as possible^ in order that fuel 
may be economized. The factors entering into the temperature of 
the feed water as it leaves the feed heater are the temperature of 
the water in the feed tank and the speed of the feed pumps. The 
quantity of drain water entering the feed tank^ the tempeiature 
of the circulating water in the condenser^ and the speed of the 
circulating pump regulate the temperature of the water in the 
feed tank. 

It must be remembered^ however, that feed heating does not result 
in economy if the back pressure on the auxiliary exhaust is raised 
to such a point as to materially decrease the efficiency of the auxiliary 
machinery. This caution should be particularly heeded in all cases 
where turbine-driven auxiliaries are installed. 

Feed heating is always economical, however, if steam that would 
otherwise be wasted is used for feed heating. 

Banked Fires. — In water-tube boilers, banked fires cause unequal 
heating of the parts of the boilers, with the resulting harmful effects, 
such as leaky seams and joints and burnt grate bars, and should not 
be allowed except in emergency or as a military necessity. In 
ordinary service, where it is not expected to use the boilers again for 
about twelve hours or more, it is better for the boilers and more 
economical to allow fires to die out. 

If the boilers are to be used again in a few hours, it is better to 
keep light spread fires and check the draft. 

Digitized by 


316 Mabikb and Naval Boilers 

Banked fires are harmful in a much less degree in fire-tube boilers 
than in water-tube boilers, as the large quantity of water contained 
in the shell and surrounding the furnaces helps to equalize the tem- 

Hauling Fires. — Fires must not be hauled except to prevent 
damage to a boiler in case of emergency. When steam is no longer 
required, the fires must be allowed to die out in the furnaces, with 
the dampers, furnaces and ash pits closed. 

Whenever any water-tube boiler is suspected of being injured 
to such an extent that the fires should be hauled, the fire doors 
must not be opened to commence this operation imtil the safety- 
valves have been lifted, stop valves closed, and the steam pressure 
reduced to less than 60 pounds. While this reduction is being 
effected, the fire and ash-pit doors must be kept closed and the ex- 
tinguishers, if fitted, must be used to quench the fire. 

Supply of Feed. — ^Boilers under steam should be fed at a regular 
rate for a definite power developed. Theoretically, at a con- 
stant speed of the engines, with boilers all of the same power and 
generating the same quantity of steam, it should be possible to 
regulate the feed check valves to a certain opening and not change 
this opening until the speed or number of boilers is chani^. 
Actually, on accoimt of the varying proficiencies of the firemen and 
the conditions of the boilers, no two boilers generate the same 
quantity of steam for any considerable time, so that it is necessary 
for the water-tenders continually to be making small adjustments 
of the check valves to keep the water at a constant level. If careful 
attention is given to the proper feeding of the boiler, any difficidties 
arising in the feeding will be detected in time to prevent accident 
and injury. 

Low Water. — Low water in a steaming boiler is of frequent 
occurrence, and is usually the result of one of the following causes: 

1. Inattention of the water-tender or the diverting of his attention 
to other duties. 

2. Faulty action of the feed pumps. 

3. Leaks in the feed discharge line. 

4. Hot or low water in the feed tanks. 

5. Defective check valve. 

6. Water gages giving false indications. 

7. Poor evaporation by the boiler (at high speeds) causing 

Digitized by 


Carb and Manaqement of Boilers 317 

When the water in a water-tube boiler drops out of sight in the 
glass and remains out of sights the fires must be hauled and the 
boiler cut out. The feed check valve should be closed to prevent 
cold water striking the parts which will become overheated. The 
stop valve should be closed to prevent steam rushing in from other 
boilers when the safety-valve is lifted to relieve the pressure on the 
weakened boiler. The fires should be damped before they are 
hauled, and then the boiler casing should be completely closed to 
prevent any air from getting to the heated parts until they are 
thoroughly cooled. In oil-burning boilers the burners should be 
shut off under such circumstances. 

Ash-Pit Doors. — ^When boilers are under steam, the automatic 
ash-pit doors should be in place and be so adjusted that they will 
close properly in case of the rupture of any pressure part of the 
boiler. The infrequency of emergencies necessitating automatic 
safety devices such as this, makes the fire-room force forgetful of 
their importance, and it is frequently necessary to remind them of 
their proper handling and care. 

Boiler Accidents. 

In all cases of accident to boilers or machinery, every endeavor 
shall be made to localize the injury. The compartment involved 
should be isolated to prevent escaping steam from getting into other 
compartments and interfering with proper attendance of other 
boilers or machinery in use. All men on duty must remain at their 
proper stations, give strict attention to the machinery in operation 
and avoid the inattention sometimes due to excitement which may 
lead to further damage. When considerable leaks of steam occur 
in a fire-room, the upper part of the compartment is generally filled 
with steam and men must not be allowed to go up the fire-room lad- 
ders at such times on account of the great danger of their being 
seriously injured or overcome by inhaling the steam. The best 
avenue of escape, if it becomes necessary to abandon the compart- 
ment, is through an opening at the level of the fire-room fioor plates. 

Whenever a serious steam leak occurs in a tube or other pressure 
part of the boiler, the following procedure should be followed: 

1. Open safety-valves as quickly as possible to relieve the pressure. 

2. Close the boiler stop valve. 

3. Notify engine-room force and tell them to keep plenty of water 
in feed tanks. 

Digitized by 


318 Marine and Naval Boilers 

4. Deaden fires (shut oflE burners if burning fuel oilj. 

5. Keep ash-pan doors and furnace doors closed until the steam 
pressure is reduced to about 50 pounds or less. (The ash-pan doors 
will have closed automatically if the rupture occurred in a part sur- 
rounding the furnace.) 

6. Keep the blowers going and increase their speed to drive the 
steam out of the fire-room. 

7. Leave the dampers open. 

8. Keep the feed check valve open^ and also put on auxiliary 
f eed^ if needed. 

9. Haul fires, and then close the boiler and allow it to cool slowly. 
If the leak is so bad that the water level cannot be maintained, 

the feeding of the boiler should be stopped. If the level can be 
maintained, an auxiliary feed pump should be started to feed the 
injured boiler, in order that the other boilers may not suffer lack of 
water on account of the extra feed to the injured one. 

The tlse of Fuel OH. 

N. I. 3122. (1) The principal points requiring especial atten- 
tion in working fuel-oil installations are : 

(a) The Oil Pressure. — This in great measure governs the rate 
of burning the oil, and shall be maintained as nearly constant aa 
possible. As far as practicable, the pulsation from the pumps shall 
be removed from the oil before it reaches the burners. This is 
accomplished by the use of air chambers fitted on the discharge side 
of the pumps and elsewhere in the piping system. The pressure 
shall be regulated according to the amount of oil required to be 
burned. For small variations in the rate of steaming, without 
changing the number of burners in use, the corresponding change 
in the quantity of oil supplied shall be made by altering the oil 
pressure and not by changing the amount of opening of the burners, 
unless a readjustment is necessary to secure a satisfactory spray. 

(b) The Air Supply. — ^This varies according to the amount of oil 
to be burned, and shall be carefully regulated to maintain a steady 
flame of about the same size from each burner and an amount of 
smoke that is just visible at the top of the smoke-pipe. Too little 
air will produce excessive smoke, and may cause flaming through the 
slots of the air cones and overheating of the cones themselves. Too 
much air, while it may prevent smoke, will reduce the efficiency of 
the boiler. The proper regulation of the velocity with which the air 

Digitized by 


CabB and MANAGEldiENT OF BoiLBBS 319 

18 admitted to the burners is important in connection with prevent- 
mg panting of the boilers, and may be accomplished by varying the 
openings through the slots in the cones when they are fitted with a 
movable register for this purpose. When not so fitted, the necessary 
regulation shall be accomplished by varying the air pressure in the 
fire-room by means of altering the speed of the fire-room blowers, 
(c) The Temperature of the Oil. — The oil is heated to make it 
thin or fluid enough for efficient spraying .at moderate pressures. 
It is foimd by experiment that considerable increase in fluidity 
is obtained by heating the oil to from 150** to 176® F., but above 
the latter temperature there is no considerable change. If heated 
much beyond 175** P., there is danger of breaking down the oil and 
clogging the heaters, strainers, burners, or pipes with the solid 
particles of carbon thus produced. It is dangerous to heat the oil 
above its flash point, because if a leak occurs the oil will issue in a 

(2) Upon starting fires in a boiler, care shall be taken before 
lighting fuel-oil burners to insure that the furnace and ash pit 
are clear of oil and well ventilated ; and, in order to avoid a possible 
back fiash, the fireman shall stand well clear of the sight-holes and 
other openings in the furnace front. In lighting burners in addition 
to those required for raising steam, the oil shall not be turned on 
until the blowers have been started and the furnace has been cleared 
of gas. Similarly, in shutting down, the blowers shall be kept run- 
ning imtil all the burners have been shut off. Should a burner 
become extinguished accidentally, the cause may be due to (a) water 
mixed with the oil coming from the oil tanks, or from leaky heaters ; 
(b) solid matter choking the burner, due either to fault of the 
strainers or to carbonizing of the oil in the burner; or (c) water 
passing over with the oil from the tanks or air chambers on the 
pumps or oil line. When a burner is choked and cannot be cleared 
by temporary alterations of the spindle adjustment, it shall be re- 
moved at once and be thoroughly cleaned. The cleaning shall be 
very carefully done, care being taken that the outlet holes are not 
roughened, enlarged, or altered in shape. Burners shall never be 
left in place disconnected. 

(3) When heaters are fitted, special effort shall be made to 
detect promptly any leaks from the oil to the steam side of the 
heater. Such leaks allow the oil to pass directly to the boiler water, 
and, in order to prevent this, the steam pressure on the heater shall 

Digitized by 


320 Marine and Naval Boilers 

be kept higher than the oil pressure^ when practicable. At least 
once during each watch the drain from the oil heaters shall be 
tested for the presence of oil^ and if oil be f ound, the heater shall 
be drained and disconnected at once. 

(4) Boilers Burning Coal and Oil. — When boilers are fitted to 
bum oil in combination with coal, it shall be borne in mind that the 
installation is designed to obtain the full power from the boilers 
when burning coal alone. The oil is provided to make it possible 
to maintain production of steam on prolonged full-power runs after 
the coal fires become dirty, or when the trimming of the coal to the 
fire-rooms becomes diflBcult. Therefore, in order to prevent undue 
forcing when burning both coal and oil, the rate of burning the oil 
shall not be allowed to exceed 16 pounds per square foot of grate 
surface per hour. In burning oil with coal, special attention shall 
be paid to the opening of the ash-pit doors for regulating the quan- 
tity of coal burned. When the fires are clean, these doors shall be 
nearly closed; and their opening shall be gradually increased as the 
fires become dirty. The fires shall be worked so that the grate is 
well covered, with no holes ; and they shall be of moderate thickness 
and of even surface. Care shall be taken in handling the fire at the 
front of the furnace to avoid blocking the air cones and overheating 
the furnace fronts or cones. The coal shall be fed in small quan- 
tities at a time, and the fire doors shall be kept open as short a time 
as possible. The fire shall be cleaned as woxdd be done when 
burning cofil alone; and., while it is being cleaned, the burners in 
that vicinity shall be shut oflE. The air pressure and the supply of 
coal and oil shall be carefully regulated, so as to produce the most 
efficient combustion of both fuels, with a minimum of smoke. 
Should excess smoke occur, the cause may be (a) fires too heavy; 
(b) insufficient air pressure in the fire-room or improper opening 
of air register; or (c) ash-pit doors open too wide, or holes in the 
fires, thus preventing a sufficient proportion of air passing through 
the air cones. 

Use of Bottom Blows. 

An increase in the salinity of the feed water in any part of the 
feed system should be investigated immediately and the cause, if 
possible, be removed. It will be found generally that the boiler 
water will show at least a few grains of salt per gallon when every 
part of the feed system is apparently in perfect condition. The 

Digitized by 


Gabb and Manaobmbnt of Boilbbs 321 

general condition of the boilers and boiler fittings^ and the age of the 
boilers, will determine the percentage of salt which it is impossible 
to avoid. An increase in the quantity of salt imder given conditions 
is an indication that something is wrong. Whether or not the in- 
crease of salt can be avoided will determine the necessity and 
frequency of the use of the bottom blow valves. The bottom blows 
are for the purpose of decreasing the quantity of solid matter in the 
boiler under steam, whether the solid matter is salt or some other 
impurity. Under normal conditions, it seldom is necessary to open 
the bottom blows. Whenever they are used, they should be cracked 
to equalize the pressure in the blowpipe and boiler, and then quickly 
be opened wide and left open for a few seconds, and then quickly 
closed. The amount of blow-down is determined by a comparison 
of the water levels in the gage glass before and after blowing. 

Emptying Boilers. 

From what has been said repeatedly about the harmful effects of 
sudden changes of temperature, it is evident that the only proper 
way to empty a boiler of hot water is to allow the boiler and water 
to cool slowly and then to run down or pump out the boiler. In 
this connection, attention may properly be called to the somewhat 
similar harmful effects of quickly reducing the pressure in emer- 
gency by means of the safety-valves. If possible, pressures and 
temperatures should be reduced slowly. 

Digitized by 




The following nUes for conducting boiler trials, code of 1899, 
have been adopted by the American Society of Mechanical Engi- 
neers : 

I. Detennine at the outset the specific object of the proposed 
trial, whether it be to ascertain (a) the capacity of the boiler, (b) 
its efficiency as a steam generator, (c) its efficiency and its defects 
under usual working conditions, (d) the economy of some particular 
kind of fuel, or (e) the effect of changes of design, proportion or 
operation, and prepare for the trial accordingly. 

II. Examine the boiler, both outside and inside; ascertain the 
dimensions of grates, heating surfaces, and all important parts, 
and make a full record describing the same, illustrating special 
features by sketches. The area of heating surfaces is to be com- 
puted from the surfaces of shells, tubes, furnaces and fire-boxes in 
contact with tlie fire or hot gases. The outside diameters of water 
tubes and the inside diameters of fire tubes are to be used in the 
computation. All surfaces below the mean water level which have 
water on one side and products of combustion on the other, are to 
be considered as water-heating surface; and all surfaces above the 
mean water level which have steam on one side and products of com- 
bustion on the other, are to be considered as superheating surface. 

III. Notice the general condition of the boiler and its equip- 
ment, and record such facts in relation thereto as bear upon the 
objects in view. 

If the object of the trial is to ascertain the maximum economy or 
capacity of the boiler as a steam-generator, the boiler and all its 
appurtenances should be put in first-class condition. Glean the 
heating surface inside and out. Bemove clinkers from the grates 
and from the sides of the furnace. Bemove all dust, soot and ashes 
from the chambers, smoke connections and fines. Close air leaks in 
the masonry and poorly fitting doors. See that the damper will open 
wide and close tight. Test for air leaks either by firing a few shovels 
of smoky fuel and immediately closing the damper, and observing 

Digitized by 



the escape of smoke through the crevices^ or by passing the flame of 
a candle over cracks in the brick-work. 

lY. Determine the character of the coal to be used. For tests of 
the efficiency or capacity of the boiler for comparison with other 
boilers^ the coal should^ if possible^ be of soine kind which is com- 
mercially regarded as a standard. For New England and that por- 
tion of the country east of the Alleghany Mountains^ good anthracite 
egg coal^ containing not over 10^ of ash^ and Clearfield (Pa.), 
Cumberland (Md.) and Pocahontas (Va.) semi-bituminous coals 
are thus regarded. West of the Alleghany Mountains, Pocahontas 
(Va.) and New River (W. Va.) semi-bituminous, and Youghio- 
gheny or Pittsburgh bituminous coals are recognized as standards. 
There is no special grade of coal mined in the western states which 
is widely recognized as of superior quality or considered as a stand- 
ard coal for boiler testing. Big Muddy lump, an Illinois coal 
mined in Jackson County, 111., is suggested as being of a sufficiently 
high grade to answer these requirements in districts where it is 
more conveniently obtainable than the other coals mentioned above. 
For tests made to determine the performance of a boiler with a 
particular kind of coal, such as may be specified in a contract for 
the sale of a boiler, j;he coal used should not be higher in ash and in 
moisture than that specified, since increase in ash and in moisture 
above a stated amount is apt to cause a falling off of both capacity 
and economy in greater proportion than the proportion of such 

V. Establish the correctness of all apparatus for weighing and 
measuring used in the test. These are : 

1. Scales for weighing coal, ashes and water. 

2. Tanks or water meters for measuring water. Water meters,' 
as a rule, should be used only as a check on other measurements. 
For accurate work the water should be weighed or measured in a 

3. Thermometers and pyrometers for taking temperatures of air, 
steam, feed-water, waste gases, etc. 

4. Pressure gages, draft gages, etc. The kind and location of the 
various pieces of testing apparatus must be left to the judgment of 
the person conducting the test, always keeping in mind the main 
object, i. e., to obtain authentic data. 

VI. See that the boiler is thoroughly heated to its usual working 
temperature before the trial. If the boiler is new and of a form 

Digitized by 


324 Mabinb and Natal Boilbbs 

provided with a brick settings it should be in use at least a week be- 
fore the trials so as to dry and heat the walls. If it has been laid 
off and has become cold^ it should be worked before the trial until 
the walls are well heated. 

YII. The boiler and connections should be proved free from 
leaks before beginning a test, and all water connections, including 
blow and extra feed pipes, should be disconnected, stopped with 
blank flanges, or bled through special openings beyond the valves, 
except the particular pipe through which the water is to be fed to 
the boiler during the trial. During the test the blow off and feed 
pipes should remain exposed to view. 

If an injector is used, it should receive steam directly through a 
felted pipe from the boiler being tested. 

If the water is metered after it passes the injector, its tempera- 
ture should be taken at the point where it leaves the injector. If 
the quantity is determined before it goes to the injector, the tem- 
perature should be determined on the suction side of the injector ; 
and if no change of temperature occurs other than that due to the 
injector, the temperature thus determined is properly that of the 
feed water. When the temperature changes between the injector 
and the boiler, as by the use of a heater or by radiation, the tempera- 
ture at which the water enters and leaves the injector and that at 
which it enters the boiler should be taken. In this case the weight 
to be used is that of the water leaving the injector, computed from 
the heat units if not directly measured, and the temperature that 
of the water entering the boiler. 

Let «;= weight of water entering the injector. 
2;= weight of steam entering the injector. 
Ai=heat units per pound of water entering the injector. 
h2=hesLt units per pound of steam entering the injector. 
A3 = heat units per pound of water leaving the injector. 

Then w -f- a? = weight of water leaving injector, and a?=tty ,*^ ,^ 

/ij— /I, 

See that the steam main is so arranged that water of condensation 
cannot run back into the boiler. 

VIII. Duration of the Test. — For tests made to ascertain either 
the maximum economy or the maximum capacity of a boiler, irre- 
spective of the particular class of service for which it is regularly 
used, the duration should be at least 10 hours of continuous run* 

Digitized by 


BoiLBR Tbsts 325 

ning. If the rate of combustion exceeds 25 pounds of coal per 
square foot of grate surface per hour, it may be stopped when a 
total of 260 pounds of coal has been burned per square foot of grate. 
In cases where the service requires continuous running for the whole 
24 hours of the day, with shifts of firemon a number of times during 
that period, it is well to continue the test for at least 24 hours. 

When it is required to ascertain the performance under the work- 
ing conditions of practical running, whether the boiler be regularly 
in use 24 hours a day or only a certain number of hours out of each 
24, the fires being banked the balance of the time, the duration 
should not be less than 24 hours. 

IX. Starting and Stopping a Test. — The conditions of the boiler 
and furnace should be, in all respects, as nearly as possible, the 
same at the end as at the beginning of the test. The steam pressure 
should be the same ; the water level should be the same ; the fire upon 
the grates should be the same in quantity and condition; and the 
walls, fines, etc., should be of the same temperature. 

Two methods of obtaining the desired equality of conditions of 
the fire may be used; viz., those which were called in the code of 
1885 ''the standard method" and ''the alternate method,*' the 
latter being employed where it is inconvenient to make use of the 
standard method. 

X. Standard Hethod of Starting and Stopping a Test. — Steam 
being raised to the working pressure, remove rapidly all the fire 
from the grate, close the damper, clean the ash pit, and, as quickly 
as possible, start a new fire with weighed coal and wood, noting the 
time and the water level * while the water is in a quiescent state just 
before lighting the fire. 

At the end of the test remove the whole fire, which has been 
burned low, clean the ash pit, note the water level when the water 
is in a quiescent state, and record the time of hauling the fire. 
The water level should be, as nearly as possible, the same as at the 
beginning of the test. If it is not the same, a correction should be 
made by computation, and not by operating the pump after the test 
is completed. 

^ The gage glass should not be blown out within an hour before the 
water level is taken at the beginning and end of a test, otherwise an 
error in the reading of the water level may be caused by a change of 
temperature and density of the water in the pipe leading from the bottom 
of the glass into the boiler. 

Digitized by 


326 Mabinb and. Naval Boilebs 

XL Alternate Method of Starting and Stopping a Test. — ^The 
boiler being thoroughly heated by a preliminary run, the fires are 
to be burned low and well cleaned. Note the amount of coal left on 
the grate as nearly as it can be estimated. Note the pressure of the 
steam and the water level. Note the time and record it as the 
starting time. Fresh coal, which has been weighed, should now be 
fired. The ash pits should be thoroughly cleaned at once after 
starting. Before the end of the test the fires should be burned low, 
just as before the start; and the fires should be cleaned in such a 
manner as to leave a bed of coal on the grates of the same depth, 
and in the same condition, as at the start. When this stage is 
reached, note the time and record it as the stopping time. The water 
level and steam pressure should previously be brought as nearly as 
possible to the same point as at the start. If the water level is not 
the same as at the start, a correction should be made by computation, 
and not by operating the pump after the test is completed. 

XII. TTniformity of Conditions. — In all trials made to ascertain 
maximum economy or capacity, the conditions should be maintained 
uniformly constant. Arrangements should be made to dispose of 
the steam so that the rate of evaporation may be kept the same from 
beginning to end. This may be accomplished in a single boiler by 
carrying the steam through a waste-steam pipe, the discharge from 
which can be regulated as desired. In a battery of boilers, in which 
only one is tested, the draft may be regulated on the remaining 
boilers, leaving the test boiler to work under a constant rate of pro- 

Uniformity of conditions should prevail as to the pressure of 
steam, the height of water, the rate of evaporation, tlie thickness of 
fire, the times of firing and quantity of coal fired at one time, and as 
to the intervals between the times of cleaning the fires. 

The method of firing to be carried on in such tests should be dic- 
tated by the expert or responsible person in charge of the test, and 
the method adopted should be adhered to by the firemen throughout 
the test. 

XIII. Keeping the Becords. — Take note of every event connected 
with the progress of the trial, however unimportant it may appear. 
Record the time of every occurrence and the time of taking every 
weight and every observation. 

The coal should be weighed and delivered to the firemen in equal 
portions, eabh sufficient for not more than one hour^s run. and a 

Digitized by 


BoiLEB Tests 327 

fresh portion should not be delivered nntil the previous one has all 
been fired. The time required to consume each portion should be 
noted, the time being recorded at the instant of firing the last of 
each portion. It is desirable that at the same time the amount of 
water fed into the boiler should be accurately noted and recorded, 
including the height of the water in the boiler, and the average 
pressure of steam and temperature of feed during the time. By 
thus recording the amount of water evaporated by successive por- 
tions of coal, the test may be divided into several periods if desired, 
and the degree of uniformity of combustion, evaporation and 
economy be analyzed for each period. In addition to these records 
of the coal and the feed water, half-hourly observations should be 
made of the temperature of the feed water, of the flue gases, of the 
external air in tiie boiler room, of the temperature of the furnace 
when a furnace pyrometer is used, and also of the pressure of the 
steam and of the readings of the instruments for determining the 
moisture in the steam. A log should be kept on properly prepared 
blanks containing columns for record of the various observations. 

When the standard method of starting and stopping the test is 
used, the hourly rate of combustion and of evaporation and the 
horse-power should be computed from the records taken during the 
time when the fires are in active condition. This time is somewhat 
less than the actual time which elapses between the beginning and 
end of the run. The loss of time due to kindling the fire at the 
beginning and burning it out at the end makes this course necessary. 

XIY. Quality of Steam. — The percentage of moisture in the 
steam should be determined by the use of either a throttling or a 
separating steam calorimeter. The sampling nozzle should be 
placed in the vertical steam pipe rising from the boiler. It shouli? 
be made of i" pipe, and should extend across the diameter of the 
steam pipe to within i" of the opposite side, being closed at 
the end and perforated with not less than twenty i" holes equally 
distributed along and around its cylindrical surface, but none of 
these holes should be nearer than i" to the inner side of the steam 
pipe. The calorimeter and the pipe leading to it should be well 
covered with felting. Whenever the indications of the throttling 
or separating calorimeters show that the percentage of moisture is 
irregular, or occasionally in excess of 3^ the results should be 
checked by a steam separator placed in the steam pipe as close to 
the boiler as convenient, with a calorimeter in the steam pipe just 

Digitized by 


328 Marine and Naval Boilers 

beyond the outlet from the separator. The drip from the separator 
should be caught and weighed, and the percentage of moisture 
computed therefrom should be added to that shown by the 

Superheating should be determined by means of a thermometer 
placed in a mercury well inserted in the steam pipe. The degree of 
superheating should be taken as the difference between the reading 
of the thermometer for superheated steam and the readings of the 
same thermometer for saturated steam at the same pressure as 
determined by a special instrument, and not by reference to steam 

XV. Sampling the Coal and Determining its Hoistuie. — ^As each 
barrow load or fresh portion of coal is taken from the coal pile, a 
representative shovelful is selected from it and placed in a barrel 
or box in a cool place and kept until the end of the trial. The 
samples are then mixed and broken into pieces not exceeding l'" in 
diameter, and reduced by the process of repeated quartering and 
crushing until a final sample weighing about 5 pounds is obtained, 
and the size of the larger pieces is such that they will pass through 
a sieve with \" meshes. From this sample two one-quart air-tight 
glass preserving jars, or other air-tight vessels which will prevent 
the escape of moisture from the sample, are to be promptly filled, 
and these samples are to be kept for subsequent determinations of 
moisture and of heating value and for chemical analysis. During 
the process of quartering, when the sample has been reduced to 
about 100 pounds, a quarter to a half of it may be taken for an 
approximate determination of moisture. This may be made by 
placing it in a shallow pan, not over 3" deep, carefully weighing it, 
and setting the pan in the hottest place that can be found* on the 
brick-work of the boiler setting or flues, keeping it there for at least 
12 hours, and then weighing it. The determination of moisture 
thus made is believed to be approximately accurate for anthracite 
and semi-bituminous coals, and also for Pittsburgh or Toughio- 
gheny coal ; but it cannot be relied upon for coals mined west of 
Pittsburgh, or for other coals containing inherent moisture. For 
these latter coals it is important that a more accurate method be 
adopted. The method recommended by the committee for all 
accurate tests, whatever the character of the coal, is described as 
follows : 

Digitized by 


BoiLBR Tbsts 329 

Take one of the samples contained in the glass jars and subject it 
to a thorough air-drying by spreading it in a thin layer and expos- 
ing it for several hours to the atmosphere of a warm room^ weighing 
it before and after, thereby determining the quantity of surface 
moisture it contains. Then crush the whole of it by running it 
through an ordinary cofifee mill adjusted so as to produce somewhat 
coarse grains (less than ^"), thoroughly mix and crush the sample, 
select from it a portion of. from 10 to 50 grams, weigh it in a 
balance which will easily show a variation as small as 1 part in 
1000, and dry it in an air or sand bath at a temperature between 
240** and 280** P. for 1 hour. Weigh it and record the loss; then 
heat and weigh it again repeatedly, at intervals of an hour or less, 
until the minimum weight has been reached and the weight begins 
to increase by oxidation of a portion of the coal. The difference 
between the original and the minimum weight is taken as the mois- 
ture in the air-dried coal. This moisture test should preferably be 
made on duplicate samples, and the results should agree within 
0.3^ to 0.4^, the mean of the two determinations being taken as the 
correct result. The sum of the percentage of moisture thus found 
and the percentage of surface moisture previously determined i^ the 
total moisture. 

XVI. Treatment of Ashes and Befuse. — ^The ashes and refuse 
are to be weighed in a dry state. If it is found desirable to show 
the principal characteristics of the ash, a sample should be sub- 
jected to a proximate analysis and the actual amount of incom- 
bustible material be determined. For elaborate trials a complete 
analysis of the ash and refuse should be made. 

XYII. Calorifio Tests and Analysis of Coal. — ^The quality of the 
fuel should be determined either by heat test or by analysis, or by 

The rational method of determining the total heat of combustion 
is to burn the sample of coal in an atmosphere of oxygen gas, the 
coal to be sampled as directed in article XV of this code. 

The chemical analysis of the coal should be made only by an 
expert chemist. The total heat of combustion computed from the 
results of the ultimate analysis may be obtained by the use of 
Dulong's formula (with constants modified by recent determina- 
tions), viz.: 14,6000 + 62,000 ^H- ^^40008, in which C, H, 

and S refer to the proportions of carbon, hydrogen, oxygen and 
sulphur, respectively, as determined by the ultimate analysis. 

Digitized by 


330 Marine and Naval Boilehs 

It is desirable that a proximate analysis should be made, thereby 
determining the relative proportions of volatile matter and fixed 
carbon. These proportions furnish an indication of the leading 
characteristics of the fuel^ and serve to fix the class to which it 
belongs. As an additional indication of the characteristics of the 
fuel^ the specific gravity should be determined. 

XVIII. Analysis of Hue Oases. — ^The analysis of the flue gases 
is an especially valuable method of determining the relative value 
of different methods of firing or of different kinds of furnaces. In 
making these analyses great care should be taken to procure average 
samples, since the composition is apt to vary at different points of 
the flue. The composition is also apt to vary from minute to minute, 
and for this reason the drawings of gas should last over a consider- 
able period of time. Where complete determinations are desired, the 
analyses should be entrusted to an expert chemist. For approximate 
determinations, the Orsatt or the Hempel apparatus may be used by 
the engineer. For the continuous indication of the amount of car- 
bonic acid present in the flue gases, an instrument may be employed 
which shows the weight of the sample of gas passing through it. 

XIX. Smoke Observations. — ^It is desirable to have a uniform 
system of determining and recording the quantity of smoke pro- 
duced where bituminous coal is used. The system conunonly em- 
ployed is to express the degree of smokiness by means of percent- 
ages dependent upon the judgment of the observer. The conunittee 
does not place much value upon a percentage method, because it 
depends so largely upon the personal element; but if this method is 
used, it is desirable that, so far as possible, a definition be given in 
explicit terms as to the basis and method employed in arriving at 
the percentage. The actual measurement of a sample of soot and 
smoke by some form of meter is to be preferred. 

XX. Miscellaneous. — In tests for purposes of scientific research, 
in which the determination of all the variables entering into the 
test is desired, certain observations should be made which are, in 
general, unnecessary for ordinary tests. These are the measure- 
ments of the air supply, the determination of its contained moisture, 
the determination of the amount of heat lost by radiation, of the 
amount of infiltration of air through the setting, and (by condensa- 
tion of all steam made by the boiler) of the total heat imparted to 
the water. 

As these determinations are rarely undertaken, it is not deemed 
advisable to give directions for making them. 

Digitized by 


BoiLBR Tbsts 331 

XXI. Calcnlations of Efficiency. — Two methods of defining and 
calculating the efficiency of a boiler are recommended. They are : 

1 Efficiency of the boiler = heat ab sorbed per lb. combustible , 
^ calorific value of 1 lb. combustible 

2. Efficiency of the boner and grate=^«fl*^«°l'j«4^^^ 

calorific value of 1 lb. coal 

The first of these is sometimes called the '^ efficiency based on 
combustible/' and the second the ^'efficiency based on coal." The 
first is recommended as a standard of comparison for all tests, and 
this is the one which is understood to be referred to when the word 
" efficiency '' alone is used without qualification. The second, how- 
ever, should be included in a report of a test, together with the 
first, whenever the object of the test is to determine the efficiency 
of the boiler and furnace together with the grate (or mechanical 
stoker), or to compare different furnaces, grates, fuels or methods of 

The heat absorbed per pound of combustible (or per pound of 
coal) is to be calculated by multiplying the equivalent evaporation 
from and at 212** per poimd combustible (or coal) by 970.4. 

XXII. The Heat Balance. — An approximate heat balance, or 
statement of the distribution of the heating value of the coal among 
the several items of heat utilized and heat lost, may be included in 
the report of a test when the analyses of the fuel and of the chimney 
gases have been made. It should be reported in the following form : 

♦ The factor of evaporation should be computed as follows : For 
wet steam, find from the steam tables the heat of the liquid, usually 
given above 32® P., and correct for temperature of feed. Multiply 
the. latent heat of evaporation by the quality. Add these two quan- 
tities together and divide by the heat of evaporation of steam at 
atmospheric pressure. 

* For superheated steam, simply substract from the total heat the 
excess of feed over 32** F. and divide as before. 

^ Made In Bureau of Steam Engineering. 

Digitized by 



Maeinb and Naval Boilers 



. U. 

B. T.U. 

Per cent. 

1. Heat absorbed by the boiler « evaporation from and at 212* per 

2. Loaa due to moisture in coal = (per cent of moisture referred 
to combustible + 100) x [(2I2 - + 970.4 + 0.48 (T - 212)] ; 
(t = temperature of air in the boiler room, T — that of the 

8. Lobs due to moisture formed by the burning of hydrogen == (per 
cent of hydrogen to combustible + 100) x 9 x [(212 - + 

07n 4 4. 4R fT 212^1 .••• 

4. •Loss due to heat carried away in the dry chimney gases = 
weight of i^'as per pound of combustible x 0.24 x iT-t)..., 
6. t Loss due to incomplete combustion of carbon = 

CO per cent C in conribustible ^ ,« ,r« 

CO. + CO'' 100 '""•'°" 
Loss due to unconsumed hydrogen and hydrocarbons, to heat- 
ing the moisture in the air, and to radiation, and loss unac- 
counted for. (Some of these losses may be separately item- 
ized, if data are obtained from which they maybe calculated). 

Totals • • •••• 


• The weight of gas per pound of carbon burned may be calculated from the 
gas analysis as follows : 

Dr, >a. per pound of carbon =L1C0,±8^+_7^0±N} , 

In which CDs. CO, O and N are the percentages by volume of the several gases. 
▲s the sampling and analysis of the gases in tne present state of the art are liable 
to considerable errors, the result of this calculation is usually only an approximate 
one. The heat balance itself is only approximate for this reason, as well as for the 
fact that it is not possible to determine accurately the percentage of unburned 
hydrogen or hydro-carbons in the flue gases. 

The weight of dry gas per pound of combustible is found by multiplying the arj 

Es per pound of carbon by the percentage of carbon in the combustible, and dlvid- 
jr by loO. 

T COt and CO are respectively the percentages by volume of carbonic acid and 
carbonic oxide in the flue gases. The quantity 10,160 equals the number of heat 
units generated by burning to carbonic acid one pound of carbon contained in 
carbonic oxide. 

XXIII. Beport of the Trial. — The (iata and results should be 
reported in the manner given in. cither one of two tables. 

These tables are not given here. The forms issued by the Bureau 
of Steam Engineering intended for the same purpose are given, as 
follows : 

Digitized by 


BoiLEH Tbsts 333 

S. E. Foim No. 104-2. 


Type of boiler ,,.. 

Diameter of shell ; top drum ; bottom drum 

Length of shell ; top drum ; bottom drum 

Tubes, number ; diameter, outside ; length. . . . ; thickness. 

Furnace, kind of 

Fomaoe, length ; w^dth ; height 

Grate surface, length ; width ; area 

Heating surface, area ; ratio to grate 

Per cent water-heating surface ; per cent superheating surface. 

Qrate bars, kind 

Qrate bars, width of air spaces ; ratio of grate to air space. . . 

Smoke-pipe, area ; height ; ratio to grate 

Water space ; steam space 

Weight of boiler and all fittings except uptakes and smoke-pipe: 

Without water 


Total with water 

Total weight per square foot of grate surface 

Total weight per square foot of heating surface 

Blower engines, kind ; dimensions of cylinders X .... X . 

Blower fan, kind ; diameter ; width 

Area of blower inlet ; outlet 

Feed heater, kind 

Feed heater, area of surface 

Economizer, kind 

Area of surface 

Air heater, kind 

Area of surface 

Feed pumps, kind ; dimensions of cylinders X .... X . 

Other boiler appurtenances 

S. E. Form No. 104-3. 


(a) Method of weighing water 

(b) Metho^ of weighing fuel 

(c) Method of determining the amount of moisture in steam: 

Kind of calorimeter used 

Distance of calorimeter from boiler 

Size, shape and description of sampling jiozzle 

<d) Method of taking temperature of and sampling flue gases. . . 
(e) Condition of boiler before and after test 

Digitized by 



Marinb and Naval Boilers 

8. B. Form No. 104-4. 

Number of test 

1. Date of test , 

2. Duration of test hrs.. 

3. Kind of fuel 

4. Kind of start 

5. State of weather 

Average Pressures. 

6. Barometer ins 

7. Steam pressure by gage lbs 

8. Force of draft at base of pipe ins. of water. 

9. Force of draft in furnace do 

10. Force of draft in ash pit do 

11. Revolutions of blower 



Average Temperatures. 

External air degrees F 

Fire-room do 

Steam do 

Feed water entering heater do 

Feed water entering economizer, .do 

Feed water entering boiler do 

Air entering ash pit do 

Escaping gases from boiler do 

Escaping gases from economizer, .do 


Kind of 

Weight of wood used in lighting fires lbs. 

Weight of coal as fired * lbs. 

Moisture in coal per cent. 

Weight of dry coal consumed lbs. 

Weight of ash and refuse lbs. 

Weight of combustible consumed lbs. 

Per cent of refuse in dry coal 

Fuel per hour. 

29. Coal consumed per hour lbs. 

30. Dry coal consumed per hour lbs. 

31. Combustible consumed per hour lbs. 

32. Coal consumed per hour per sq. ft Q. S lbs. 

33. Dry coal consumed per hour per sq. ft Q. S lbs. 

34. Combustible consumed per hour per sq. ft. Q. S lbs. 

* iDclodlng equivalent of wood used in Ilffhtlng flree. 

Digitized by 


BoiLBR Tests 335 

8. E. Form No. 104-6. 

Number of test 

36. Coal per hour per sq. ft H. S lbs 

36. Dry coal per hour per sq. ft. H. S lbs 

37. Combustible per hour per sq. ft. H. S lbs 

Quality of Steam. 

38. Per cent of moisture in steam 

39. Degrees of superheating 

40. Quality of steam (dry steam = 100) 


41. Total weight of water fed to boiler * lbs ■ 

42. Water actually evavorated, corrected for quality 

of steam (40 by 41) lbs 

43. Factor of evaporation 

44. Equivalent water evaporated into dry steam from 

and at 212« (42 by 43) lbs 

Water per Hour. 

45. Water evaporated per hour, corrected for quality 

of steam lbs 

46. Equivalent evaporation from and at 212"^ 

47. Equivalent evaporation from and at 212"^ per sq. 

ft G. S IbB 

48. Same per sq. ft of heating surface lbs 

Economic Results. 

49. Water apparently evaporated under actual con- 

ditions per lb. of coal as fired (41 -h 23) lbs 

60. Apparent equivalent evaporation from and at 212° 

per lb. of coal including moisture (44 -:. 23) . . . .lbs 

61. Equivalent evaporation from and at 212"^ per lb. of 

dry coal (44 -j- 26) lbs 

62. Equivalent evaporation from and at 212* per lb. of 

combustible (44 -s- 27) lbs 

63. Efficiency of boiler; heat absorbed by the boiler 

per lb. of combustible divided by the heat value 

of 1 lb. of combustible. (See Sheet No. 6) 

64. Efficiency of boiler, including grate; heat absorbed 

by the boiler per lb. of dry coal, divided by the 

heat value of 1 lb. of dry coal. (See Sheet No. 6) 

Remarks and Observations. 
66. Principal data taken every ; 

66. Percentage of smoke as observed 

67. Method of observing same 

68. Kind of firing (spreading, alternate or coking) 

69. Average thickness of fires 

60. Average intervals between firings for each furnace 

during time fires were in normal condition 

61. Average interval between times of breaking up 

62. Efficiency of firemen; expert, average or poor 

* Corrected for Inequality of water level and eteam pressure at beginning and 
end of teat 

Digitized by 



Marinr and Naval Boilers 

S. E. Form No. 106-6. 




Per eeni. 

Fixed carbon 

Per etni. 

Volatile matter 






Sulphur separately determined 


Pw cent. 

Per eeni. 

Carbon (C) ... 
Hydrogen (H) 
Oxygen (O) ... 
Nitrogen (N) , 
Sulphur (S) .. 


Total 100.00 100.00 

Moisture in sample of fuel as received I 



Earthy matter. 

Per cent. 


Kind of calorimeter used 

Calorific value by calorimeter, per pound of dry coal B. T. U 

Calorific value by calorimeter, per pound of combustible Da 

Calorific value by analysis, per pound of dry coal Da 

Calorific value by analysis, per pound of combustible Do. 


Carbon dioxide (CO,) 

Oxygen (O) 

Carbon monoxide (CO) 

Hydrogen and hydrocarbons.. 
Nitrogen (N) (by difference) . 


Pep cent. 


Digitized by 


BoiLBR Tbsts 337 

For naval purpoBes^ boilers are generally tested in order to deter- 
mine: (a) The evaporative eflBeiency of different types nnder the 
same conditions^ (b) the evaporative efficiency of the same boiler 
under different conditions^ and (c) the values of different fuels in 
the same boiler under the same conditions. To determine the evapo- 
rative efficiency^ the boiler tests are generally made on shore before 
the boiler has been installed. They may be made on board ship 
with the boiler connected to the engines^ in which case the engines 
are tested at the same time. 

When a naval boiler is tested for any purpose, the code of rules 
given previously should be followed carefully in order that the 
results may be compared with similar tests of other boilers. 

The object of the test is always to obtain reliable data, and no 
point that in any way bears on the test, no matter how insignificant 
it may seem, should fail to be accurately recorded. 

All data should be carefully taken and accurately recorded. 

Instruments should be calibrated and records be made both before 
and after a test. The thermometers should be graduated to read to 
one-tenth of a degree. 

Every detail and every happening during the test should be accu- 
rately recorded, giving the time. 

The apparatus used and the methods of operation are described 
in Appendix under the following heads, among others : 

Hays^ gas analysis. 

Mahler's fuel calorimeter. 

Pensky-Martens flash-point tester. 

Methods and apparatus in testing liquid fuel. 

Carpenter's throttling calorimeter. 

Carpenter's improved separating calorimeter. 

Barrus' draft gage. 

Le Chatelier's pyrometer. 

Ashcrof t gage-testing set. 

Digitized by 


Digitized by 





Th6 following accessories are necessary to the eflScient care and 
management of a boiler plant: 

1. Steam calorimeters. 

2. Chemical testing outfit. 

3. Thermometers. 

4. Pjrrometers. 

5. 6as-analysis outfit. 

6. Fuel-testing outfit. 

7. Liquid-fuel portable test outfit. 

8. Gage-testing outfit. 

9. Draft gage. 
10. Smoke chart. 

Steam Calorimeters. 

Steam calorimeters are used for measuring the amount of mois- 
ture in the steam ; from that measurement the quality is determined. 
There are three general classes in common use: (1) The super- 
heating or throttling; (2) the separating; and (3.) the condensing 

One type of superheating and one of separating calorimeters will 
l>e described. 

* By courteous permission of Commander U. T. Holmes, U. S. N., the 
cuts and descriptions of the throttling calorimeter and of hoth kinds of 
fuel-testing outfits were taken from Holmes' Experimental Engineering, 
1911 edition. The descriptions have, in some cases, been slightly changed 
and shortened. The description of the proximate analysis of coal is also 
taken from Holmes. 

Digitized by 


340 Appbndix 

Carpenter's Throttling Calorimeters. — Fig. 103 shows Prof. Car- 
penter's throttling calorimeter. It consists of a small vessel A, to 
which steam is supplied throngh a stop valve and converging nozzle 
B, The vessel contains in its center a very deep cup, into which a 
thermometer is inserted for determining the temperature of the 
steam in the calorimeter. A cock C connects to a mercury-filled 
manometer for measuring the pressure of the steam in the calo- 
rimeter. The exhaust steam is discharged from the lower part of 
the calorimeter and is permitted to escape freely. 

Fio. 103. — Carpenter's Throttling Calorimeter. 

The principle of its operation follows from the superheating of 
steam when it is allowed to expand freely without doing work. The 
whole amoimt of heat in the steam must remain constant, but the 
total heat of vaporization being greater at a higher than at a lower 
pressure, the difference goes to superheat the steam of lower pres- 
sure. Let 

Pj = boiler pressure, absolute. 
Pj= pressure in calorimeter, absolute. 
to = temperature in calorimeter. 
Li and i3i = latent heat and sensible heat corresponding to p|. 
ffj and ^2= total heat and temperature corresponding to p,. 
«= specific heat of steam, 
a? = quality of steam required. 

Digitized by 


Appendix 341 

The heat in a pound of steam flowing to the orifice will be 

and the heat in a pound of steam in the calorimeter after passing 
through the orifice will be 

Assuming that no heat is lost or converted into work, these two 
expressions must be equal, from which 

^_ H^'hs(t,-t^)-S, _H ,^S^-hs(t,^U ) (1) 

Specific heats of superheated steam is taken as .48 ; and H^, 8^, L^ 
and i^ are found from the steam table. 1— ir=the percentage of 
moisture in the steam. 

In practical use of this instrument, it is customary to exhaust at 
atmospheric pressure, so that the normal temperature in the calorim- 
eter is the boiling-point at atmospheric pressure. H^ then becomes 
1147 from the steam tables, and ^2 becomes 212. 

Calibration Method. — The throttling calorimeter is frequently 
used to determine the quality of steam at a constant pressure, as in 
boiler tests. In such cases, if the discharge valve on the steam line 
is closed so that the only outlet is through the calorimeter, dry 
saturated steam will flow into it. Let T be the corresponding tem- 
perature in the calorimeter. Equation (1) then becomes 

During the test, if t be the observed temperature in the calorim- 
eter, the boiler pressure being the same as before, we have 

^-- L, 

and the percentage of moisture equals 

If a? is greater than imity, the steam is superheated. 

Limitations of Throttling Calorimeter. — If the percentage of 
moisture is so great that the steam, expanding into the calorimeter, 
does not become completely dried, the instrument is of no value. 
The theoretical limit is found for any initial temperature t^ by 
putting te=t2 in equation (1). The practical limit is somewhat 
lower, and varies from 2.3;^ of moisture at 50 pounds boiler pressure 
to about 7^ at 300 poimds. 

Digitized by 


842 Appendix 

The range of the instrument can be increased by connecting the 
exhaust to a condenser. Thus, with a vacuum of 28" and a steam 

Fig. 104. — Carpenter's Improved Separating Calorimeter. 

pressure of 50 pounds gage, the limit percentage of moisture would 
be about 8^. 

For small percentages of moisture the throttling calorimeter is 
the handiest and most accurate form of apparatus. The sampling 

Digitized by 


Appendix 343 

nozzle of this instrument must extend almost across the steam pipes 
and have a sufiQcient number of small holes in it to insure its get- 
ting an average sample of the steam. To obtain reliable readings^ 
the calorimeter should be thoroughly warmed up; and if readings 
are taken at frequent intervals, steam should be blown through con- 
tinuously. The calorimeter and the connection to the steam pipe 
must be well lagged to prevent loss of heat by radiation. 

Carpenter's improved separating calorimeter, shown in Fig. 104, 
contains two vessels, one inside the other. The outer surrounds the 
inner, leaving a space which serves as a steam jacket. The inner 
vessel is provided with a glass water gage 10 and scale 12. 

The steam imder test is admitted through pipe 6, striking the 
bottom of a perforated cup 14, and is deflected nearly 180**. The 
water is thrown oflE and passes through the perforations into the 
inner vessel 3, where the amount is indicated by the graduated 
scale 12 on the gage glass. The steam passes across the top of the 
perforated cup and into the outside chamber, from which it is dis- 
charged through a small orifice 8, of known area, in the bottom 
part. The orifice 8 is so small in comparison with any section of 
the steam pipe or throttle valve that there is no sensible reduction 
in pressure by passing through the calorimeter. The pressure in the 
outer chamber being the same as that in the inner, it has the same 
temperature, and consequently there is no loss by radiation from the 
interior surface except that which takes place from the exposed 
surface of the gage glass. 

It has been demonstrated that the flow of steam through a small 
orifice is proportional to the absolute steam pressure, until the 
pressure against which the flow takes place equals or exceeds 0.6 
of that in the vessel under pressure. A special form of steam gage 
is placed on the outer chamber, the inner circle of which shows the 
gage pressure, while the outer circle shows the number of pounds of 
steam that will escape through the orifice in 10 minutes of time. 

The scale 12 is graduated to hundredths of a pound, and shows 
the weight of water contained in the inner vessel. The instrument 
is operated at a constant pressure for 10 minutes, and w, the weight 
of water collected, is read oflE; also W, the weight of dry steam that 
escapes through the orifice, is read off on the outer circle of the 
steam gage. Then 

x= ■= , and l — x= 

W-hw W-hw 


Digitized by 


344 Appendix 

The separating calorimeter is accurate and applicable in all tatses 
where the steam contains moisture. It is not applicable with super- 
heated steam. 

The sampling nozzle in the steam pipe must be fitted to get an 
average sample of the steam^ and the instrument and its connections 
must be well lagged. 

Corrosion Indicators. 

The Action of Corrosion as Shown by Indicators. — Doctors Gush- 
man' and Walker have devised a means of showing the action of 
corrosion on iron and steel in what they call the ferroxyl mount. 
This mount is made as follows: A 1^^ solution of agar-agar (a 
vegetable gelatine) in distilled water is boiled for an hour, and 
is then made rigidly neutral, i. e., neither acid nor alkaline. While 
the solution is hot, a few drops of each of the indicators, ferricyanide 
of potassium and phenolphthalein, are poured into it. A thin film 
of this solution is poured over the bottom of a white dish and allowed 
to cool until stiif . The specimens of metal are placed on this film, 
and enough more of the hot solution is poured over them to cover 
them completely. The mount is then set away in a dark place and 
allowed to stiflfen. When the solution cools, it forms a stiff, trans- 
parent jelly, in which the metal specimens are plainly visible. The 
mount can be kept almost indefinitely if a thin layer of alcohol is 
kept over its surface. Where the iron corrodes at its points of high 
solution tension, the ferricyanide combines with the iron ions, and 
forms a deep-blue compound known as TurnbulVs blue. At points 
of low solution tension, where the hydrogen ion is giving up its 
charge, the hydroxyl ion (OH) combines with the phenolphthalein 
and forms a red compound. These colors appear very shortly after 
the mount is prepared. If the specimen of iron is pure and homo- 
geneous as regards the states of stress of the molecules in its sur- 
faces, there will be no color reactions and no corrosion. 

When the mount is prepared properly and the color reactions 
develop, the difference of potential and current flowing from the 
blue areas to those of red can be measured by means of a properly 
fitted potentiometer. 

If a specimen of pure iron is prepared in such a way that every 
point in its surface has the same solution tension, and is then placed 
alone in the mount, there will be no color reactions and no corrosion. 
If it is removed from the mount and connected by a metal wire to 

Digitized by 


Appendix 346 

another specimen of a metal of lower solution tension^ prepared in 
the same way^ and the two are then placed in a monnt^ the blue will 
develop all over the iron and the red all over the second specimen of 
lower tension. If the second specimen is of higher solution tension 
than the iron^ and is prepared and connected as above^ the red will 
develop all over the iron, and the color of the compoimd formed by 
the ions of the second metal with the f erricyanide will develop all 
over the second specimen. This color may not be blue. The colors 
in the mount showing that corrosion is taking place are not the 
same with all metals ; with zinc the anode is white. 

Practical Besults from the Use of the Ferrozyl Mount. — ^A speci- 
men of ordinarily good boiler plate steel prepared alone in this 
mount and preserved for some time will show red and blue all over 
its surface. On some days^ areas that were red the day before will 
be blue, and vice versa. The colors will be shifting from time to 
time, with no permanent areas of color. This is due to the fact that 
there is very little difference between the solution tensions of the 
different points. The surface that is of high solution tension may 
have the cause for the high tension corroded away and a new sur- 
face exposed by tomorrow that has a lower tension than that of the 
lowest point of today. A plate that will give this reversible color 
reaction in the mount will corrode evenly all over if immersed in 
water. If the specimen, when developed in the mount, shows per- 
manent blue and red areas over its surface, the metal has permanent 
points of high and low solution tension; and if subjected to the 
action of water for some length of time, deep pits will be found 
under the blue spots and the surface imder the red will remain 

When iron is immersed in water, it corrodes in one of the two 
following ways: (1) Evenly all over the surface, i. e., the areas of 
high and low solution tension vary from time to time; and (2) in 
spots on the surface, other adjacent spots remaining unaffected, 
i. e., the areas of high and low solution tension are permanent. 
Corrosion in the second way is the most harmful form, and is known 
as pitting. When a plate, tube or pipe is pitting, it will last only 
the length of time that it takes the point of highest permanent solu- 
tion tension to pit through, t. e., its life is the life of the point that 
pits through the quickest; while if it is corroding evenly, it will last 
much longer. 

Digitized by 


846 Appendix 

Thermometers and Pyrometers. 

Thermometers. — Ordinary glass mercurial thermometers are used 
for measuring temperatures of feed water, saturated steam and 
air when these temperatures are not higher than 500^ F. 

Thermometers are placed in so-called thermometer wells, which 
screw through the container casing and extend well into the current 
of gas or liquid to be measured. The bottom of the well should 
be filled with mercury or mineral oil of high boiling-point. The 
thermometer should be inserted into the well so that only a few 
degrees on the stem below the expected mean temperature should 
be visible. This obviates the necessity for a stem correction. 

Stem Correction. — If the stem of the thermometer is not sub- 
merged to the height of the mercury, a stem correction must be 
made to compensate for the difference in expansion of the glass 
and the mercury. 

A second thermometer is secured by pieces of string or wire to 
the one on which the readings are taken ; and the bulb of the second 
thermometer is wrapped with waste, in order that it may show the 
temperature of the stem to which it is attached. The correction to 
be applied to the reading of the first thermometer is given by the 
formula : 

Stem correction =.000088 uiT-t), 

where ti= number of degrees projecting from liquid, 

r= reading of immersed thermometer in degrees F., 
<= reading of auxiliary (second) thermometer in degrees P. 

This correction is always positive. 

Pyrometers. — For temperatures above 600® F., pyrometers must 
be used. These are of several forms, as (1) pneumatic, (2) mer- 
curial, (3) expansion, (4) calorimetric, (6) thermo-electric, (6) 
resistance, and (7) reflecting. 

Le Chatelier's Pyrometer. — This is a most reliable instrument 
for measuring high temperatures. It consists of a thermo-element 
composed of a platinum wire and another of an alloy of platinum 
and rhodium. The wires are insulated by a thin porcelain tube, 
and the junction is protected from the gases by a larger, closed 
porcelain tube. The current of electricity, generated by exposing 
the junction to heat, is measured by a suitable galvanometer, which 
has a carefully calibrated temperature scale besides the voltage scale. 
The junction of the thermo-couple is in the form of a small ball 
or button. 

Digitized by 




Fig. 106 shows an improved form of this instrument devised by 
the Vulcan Manufacturing Company, of Pittsburgh.* This form 
was designed for use in ascertaining the temperatures of molten 
metal, for which purpose the porcelain tubes would not answer. 
Even with the ordinary measurements of the gases of combustion, 
the porcelain tubes have to be handled with great care to prevent 

An iron tube, through which run the wires of the couple, has a 
connection at one end for the clay tip which protects the junction, 
and, at the other end, a terminal box for the copper wire connections 
to the galvanometer. The wires are covered with asbestos for 
insulation from each other and from the iron pipe, and are covered 
by an asbestos tube where they pass through the fire-clay tip. The 

FiQ. 106.— Le Chatelier's Pyrometer. 

connection for this tip is interchangeable, so that the tip may be 
secured at an angle, as in the figure, or straight. The rest of the 
instrument is fully explained by the figure. 

The galvanometer used is a D^Arsonval, specially made and cali- 
brated for industrial purposes, the original form, with a reflectinij 
mirror, and capable of registering to i^, being too cumbersome and 
delicate. The sensitiveness of the couple, even when protected by 
a refractory material, is such that, when it is plunged cold into the 
melted iron, the reading is obtained in 1} minutes. When it is 
heated to redness beforehand, this time is reduced to a few seconds. 

An automatic recording device is sometimes added. 

*From a paper on "The Melting Point of Cast Iron/' by Dr. It 
Moldenke, reprinted in the Journal of the American Society of Naval 
Engineers, Vol. X. 

Digitized by 


348 Appendix 

Gas-Analysis Outfits. 

These outfits are constructed on the principle of measuring the 
volume of a gaseous mixture^ treating it with a chemical that 
absorbs one of the constituents, and then, when the volume is 
remeasured, calculating the percentage volume of the absorbed 
constituent from the difference in the first and second volumetric 
measurements. The percentage volume of any absorbable gas con- 
stituent can be determined by use of the analysis outfits, but their 
principal use in the navy occurs in the analysis of the gases of 
combustion, carbon dioxide (GOa)^ oxygen (0) and carbonic oxide 
(CO). The gases are drawn through sampling pipes from the fur- 
nace, from amongst the tubes or from the uptake. In collecting 
gas for examination, care must be taken that the sampling pipes 
reach to about the middle of the gas current, in order to get an 
average sample. 

Several kinds of gas-analysis outfits have been used, among which 
are the Elliott, the Orsatt-Muencke and the Hays. The last-named 
is supplied to many vessels in the United States Navy, and its in- 
troduction has resulted in increased efficiency of firing, with conse- 
quent reduction in fuel consumption. 

Hays Gas-Analysis Apparatus. — ^The Hays apparatus is shown in 
Fig. 107, and consists of the following essential parts : 

1. The measuring burette A'. 

2. The leveling bottle C, filled with water made slightly acid. 

3. The absorption vessel B. 

4. The vessel F, which holds the absorption liquid. 

5. The aspirator P and its tubing. 

There is, in addition, a funnel E, a beaker I, a collecting bottle 
7 and numerous pinch-cocks to allow proper manipulation of the 
gases and fiuids ; all of these can be seen on the sketch. 

To enter into a little more detailed description of the essential 
parts of the apparatus, the burette A' is graduated from zero to 21, 
the zero being near the bottom. A' is connected to the leveling 
bottle C, which is kept open to the atmosphere. When the leveling 
bottle is lowered and the proper cocks are opened, and the aspirator 
P is worked, gas will be pumped through the sampling pipe and A' 
will fill. If is raised, with the cocks above and to right and left 
of A* closed, the water will rise toward the zero of A\ By opening 
slightly the pinch-cock on 17, as C is raised, enough gas will be 
forced out of A' to allow the water level in C to come to the height 

Digitized by 


Appendix 349 

of the zero in A' , As is open to the atmosphere, A' will then be 
filled down to the zero with gas under atmospheric pressure, a con- 
dition that must be fulfilled accurately before any test is started. 
In order to obtain this condition, the eye must be on the same level 
as the zero in A' , and the water level in G must be brought to the 
same horizontal line while manipulating the pinch-cock in Z7. A* 

Fio. 107. — Hays Gas-Analysis Apparatus. 

is surrounded by water in the space enclosed by -4, to keep the gas 
at uniform temperature during the experiment. To avoid breakage, 
A is held in the center of its compartment by the springs A^. As 
can be seen from the sketch. A* is connected at its top to the sam- 
pling pipe through F, and by tubing to B and 7. 

The vessel B is connected to A' by the tubing as shown; one 
branch goes up to the funnel E and one down to the vessel F, The 

Digitized by 


350 Appskdix 

bulb of £ up to 3f is filled with fine copper wire, which, when the 
absorbing liquid is forced down into F by the gas under treatment, 
exposes the gas to a large area of wet absorption surface. The vessel 
F is used to carry the absorbing liquid; it has an opening S near 
the top for filling, and a drain H at the bottom. F is filled to near 
the top with the absorbing liquid before any gas is drawn into A' 
for analysis. Then by raising C, with U open, the water can be 
made to rise, filling A'; by closing U and lowering C, the absorbing 
liquid will rise to M, This is the condition of the absorbing liquid 
at the beginning of an operation. 

The analysis is, in brief, as follows : A sample of gas is drawn 
into A', filling it from zero to L. This gas is imder atmospheric 
pressure, as the top of C is open, and the eye, the water in G and 
the zero are in same horizontal plane. By opening L and raising 
C until the water enters the bottom of the capillary tube at top of 
A', the gas is forced into the absorbing liquid in B. 

It takes about 1 minute for the absorption of GO2, and about 5 
minutes each for and CO. C is now lowered until the absorbing 
liquid comes back to M, and the measurement is read oif on A\ 

A' is graduated to read in percentage of volume. The reason for 
not graduating the burette to over 21^ is that, in the principal use 
of this apparatus, analysis of gases of combustion, the sum of the 
percentage volumes of COj, and CO never amoimts to over 21^ 
of the whole volume. 

All readings should be made on the bottom of the meniscus, or 
curve of water, in the burette; it is essential to have C open, and 
to have the eye in the same horizontal plane with the water level 
in C and in A'. 

Suppose, for instance, that the analysis was started with the gas 
mixture filling the space from zero to L, If, after the absorption 
of gas, the water in C and A' balances, say at 12, then 12j^ of the 
original volume was absorbed. If another constituent of the same 
gas is now absorbed and the second reading is, say, 16, then the 
second gas absorbed occupied 16 — 12 or of the original volume. 
Suppose a third constituent is now absorbed and the reading at 
completion of the absorption is 17.5, then the third constituent 
occupied 17.5 — 16 = 1.5j< of the original volume. 

After making the determinations for one constituent of the 
gas mixture, drain B and i^ and wash them out well with dis- 
tilled water before putting in the new absorbent solution. Some- 

Digitized by 


Appendix 361 

times it is convenient to make several COj determinations be- 
fore stopping to detennine the percentages of and CO. Aftei 
each CO2 absorption, pass the residue into V by opening Y and 
raising C until a composite sample is obtained, which can be 
used for analysis of CO and 0. As each residue of gas is passed 
into V, part of the water will be displaced from V through the tube 
T. If a large number of tests have been made, V will not hold all 
the residues; so 5^ of each residue may be taken. For example: 
The percentage of CO2 is 12, the water standing at the 12 mark on 
the " second reading.^' This leaves a residue of 88. 0% of 88 is 4.4. 
Passing this quantity of gas into V would bring the water level in 
the burette up to 16.4. The leveling bottle should be used to make 
sure that the 16.4 reading is made under atmospheric pressure. 

When through with the COj analysis, compute the average of all 
of the determinations made. We will assume that it is 10^. Fill 
the beaker / with water, submerge the open end of T and draw gas 
from y into the burette. Level the gas on the lOjf mark, expelling 
surplus gas through V, Now proceed with, the oxygen absorption^ 
The gas must be passed several times into the oxygen absorbent in 
B, measuring each time in A' until no more gas will be absorbed. 
Assuming that the level becomes stable at 19, the percentage of oxy- 
gen in the mixture is 19 — 10 or 9. Now draw oflE the oxygen al^- 
sorbent, being careful that B and F do not admit air, and proceed 
with the absorption of CO, using the proper absorbent. 

As the CO absorption may result in generation of heat, water 
should be flowed into B to cool the gas before the final measurement 
is taken. At the end of the absorption of CO, read the burette. 
We assumed that the reading after the absorption of was 19. If, 
after the CO is absorbed, the reading is, say, 19.5, the percentage of 
CO is 19.5-19 or one-half of 1^. 

In the analysis of gases of combustion, the constituents must be 
taken in the order COj, and CO, as the absorption liouid for CO 
will take in solution some of the oxygen, and that for oxygen will 
take in solution some of the COg. 

The absorbents are: (1) For CO2, potassic hydrate, prepared by 
dissolving 1 part (by weight) of caustic po^«ish (commercial stick 
form) in 2 parts distilled water (by weight) ; (2) for free oxygen, 
potassic pyrogallate, prepared by mixing together 5 grams pyro- 
gallic acid in 15 cc. distilled water and 180 grams of caustic potash 
f commercial stick form) which has been dissolved in 80 cc. of dis- 

Digitized by 


862 Appendix 

tilled water; ♦ (3) for CO, two absorbents are in use: (A) cuproiiB 
chloride solution in HGl^ prepared by saturating distilled water 
with cuprous chloride and adding an equal volume of concentrated 
HGl, or t(B) anunoniacal cuprous chloride, prepared as follows: 
(z) 200 grams commercial cuprous chloride are shaken in a closed 
flask with a solution of ammonium chloride (250 grams ammonium 
chloride in 760 cc. distilled water) ; (y) to every three volumes of 
this mixture 1 volume of ammonia (sp. gr. .91) is added, (x) and 
(y) are kept separate, and are mixed when needed; if kept mixed, a 
clean copper wire must be kept in the bottle. The absorption 
values per cc. of the reagents are about: (1) 40 cc. of CO,, (2) 
22 cc. of 0, (3A) 6 cc. of CO, and (SB) 16 cc. of CO. 

Notes and Precautions in Begard to the Analysis. — In order to 
clear A' of air in preparation for a test, raise Q with TJ open ; the 
water will go up to the top of A', Now lower C, close TJ and work 
the aspirator. Oas will be pimiped through the burette, and will 
bubble out of the leveling bottle C, P must be worked until the 
operator is satisfied that all the air in the sampling pipe has been 
pumped through and a fair sample of gas is coming into the burette. 

A book of detailed instruction is furnished with each apparatus. 

From the fact that all boilers do not steam with equal efficiency 
at the same percentage of CO,, and that CO, alone is not the absolute 
guide to maximum efficiency, it is believed that the best instrument 
for gas analysis is one in which the percentages of CO,, CO and 
in each sample can be quickly determined. The Hays instrument is 
satisfactory for use where only the CO, is to be measured. Where it 
is desired to measure the CO,, and CO in each sample, this instru- 
ment is cumbersome and requires much time. 

Orsatt-Huencke Apparatus. — The Orsatt-Muencke apparatus, 
shown in Fig. 107a, is one in which the three reagents are carried 
in separate pipettes A, A' and A'\ B is the graduated burette con- 
nected to leveling bottle Z" by a rubber hose, and surrounded by a 
water jacket. The reagents, instead of being put into one tube suc- 
cessively, are kept in separate treating pipettes. A, A', A". These 
are U-shaped, with one end of each connected by rubber tubing 
and a stop-cock to the pipe which supplies the gas to B from P. 

* The oxygen should be measured at a temperature higher than 60* F 
PTTOgallic acid, a white powder, comes in a dark bottle or dark wrapper 
and Is affected by light The pyrogallate solution should be kept in a 
dark bottle, tightly stoppered. 

t Used by Bureau of Mines. 

Digitized by 


Appbkdix 353 

The other ends of il'and A" are connected to two siphon bottles, 
forming a water seal to prevent air from the atmosphere from 
getting to the reagents. These siphon bottles (not shown) and the 
other' end of A are open to the atmosphere. To increase the absorb- 
ing surface of the reagents, the pipettes are filled with glass tubes. 
The reagents are the same as given imder the Hays' apparatus above. 

Fig. 107a. — Orsatt-Muencke Apparatus. 

The order in which the gases are absorbed is the same, the reagent 
for CO, being in the pipette A nearest the measuring tube, that for 
in A' and that for CO in A''. 

In beginning an analysis, the reagents must be adjusted in the 
capillary tubes so that the level will be at a mark at the top of the 
pipette near the rubber connector. After the apparatus has been 
connected to the aspirator, and the leveling bottle has been filled 
with water, draw enough gas into the measuring tube to fill it, by 

Digitized by 


364 Appendix 

lowering the bottle and opening the top pipe to the aspirator con- 
nection. This gas is then discharged by raising the bottle, the 
apparatus and connections thus being cleared of air. 

Now draw in 100 cc. of the gas, observing the same precautions 
in measuring as given above. Then open the cock on the first 
pipette, and allow the reagent in it to absorb the carbon dioxide, 
by running the gas in and out of the pipette about four times. At 
the last time, the reagent must be allowed to fill the leg next to the 
measuring tube up to the mark. A rubber bag is usually provided for 
the purpose of causing alternate suction and pressure in the open 
end of the pipette, and to keep the air from the reagent. In order 
to be sure that the absorption of GO, is complete, the test should 
be repeated until the last two readings agree within 0.1^. The same 
must be done with the tests for and GO, except that in the last 
case the readings must agree exactly. 

After the absorption of GOj, and the return of the remaining 
volume of gas to the measuring tube, wait one minute before taking 
the reading, in order to let the water from the sides of the tube 
drain down. Owing to the water jacket on the measuring tube, 
two meniscuses will appear when looking at the scale. So long as 
the same meniscus is read for the whole analysis, no difference will 
be made. It is best to read the bottom of a meniscus always. 

The operation is next repeated for the absorption of the 0, and 
then for the GO, each requiring a longer time than the preceding 
one. The reduction in volume each time is, as bef g;re, the percent- 
age of the particular gas in the mixture as drawn from the smoke- 
pipe, the remainder, after those gases have been absorbed, being 
classed as nitrogen. When transferring the gas during these 
operations, do not let the reagents, especially the caustic potash or 
pyrogallate, get into the measuring tube, as the water in the bottle 
must then be changed. Should a little water be allowed to get 
into the treating pipettes during a transfer, it will do no harm. 
About twenty minutes are required for an analysis by an expert 
with one apparatus. If two are used, two analyses may be made 
in twenty-five minutes. 

Deductions from Besults of Gas Analysis. — This analysis takes 
into account and measures the volumes of the dry gases. If the 
combustion were perfect and were accomplished with the exact 
amount of oxygen to provide for the chemical combination of the 
constituents of the fuel, the smoke-pipe gas analysis would show only 

Digitized by 


Appendix 355 

CO,^ and nitrogen (by difference) . The H,0 or steam gas would not 
be measured. 

To obtain perfect combustion of any f uel^ it is required that ex- 
cess oxygen above the theoretical amount be supplied; in practice^ 
when combustion is as nearly perfect as possible, the analysis of the 
gases of combustion always shows CO2, and N. 

When the percentage of in the analysis is less than about 4, GO 
is founds indicating incomplete combustion due to insufficient excess 
of oxygen. This may be on acco^mt of the fires being too heavy, or 
the draft being too light, or both. 

When the analysis shows over 8j< of oxygen, it is found by practice 
that the excess of is too great, on account of the fires being too 
light, or the draft being too heavy, or both, with a consequent loss 
of heat, due to the excess of air that has to be heated. 

The presence of GO in the smoke-pipe gases indicates imperfect 
combustion and a consequent loss of heat. Each 1^ of CO found 
indicates a loss of about 5^ of the heating value of good steaming 

GO and appearing together indicate that the air and combustible 
gases are not properly mixed, or that they are chilled below the igni- 
tion temperature by the heating surfaces of the boiler before they 
are completely burned. 

A high percentage of CO,, ^^ to 8^ 0, and any GO indicates that 
the rate of combustion of that fuel in that boiler is too high and the 
combustible gases and oxygen are chilled before they are all burned. 

High percentages of and GO, in the same sample are never 

The percentage of N is found by taking 100- (GOj-f-GO-f-0). 

Where carbon is completely burned to GO,, either with or without 
excess of air, the simi of GO, and should equal 20.9^ and the N 
should equal 79.1;^. (See composition of air.) Carbon burned to 
GO only, without excess of air, would give a gas containing 34.6j< 
GO and 66.6}< N. Hydrogen burned in the air without excess 
would give a gas 100^ N. 

// the sum of the percentages of CO^, CO and is less than 19, 
the analysis must be looked on with siLspicion. 

Calculations from the Besults of Analyses. — One of the principal 
resxdts derived from gas and coal analyses is the heat balance, which 

(A) The calorific value of the fuel (Dulong's formula, p. 329). 

(B) The heat absorbed by the boiler. 

Digitized by 


356 Appbndix 

(G) The loss due to the sensible heat in the smoke-pipe or waste 

(D) The loss due to latent heat in steam gases in smoke-pipe 

(E) Loss due to incomplete combustion. 

(F) Other losses due to radiation and otherwise unaccounted for. 

(A) Calorific Value of the Fuel. — Suppose the chemical analysis 
of a coal as fired gave, in per cent, 83.5 C, 4.8 H, 3.2 0, 1.2 N, 
0.5 S, 1.5 moisture and 5.3 ash. 

To reduce this to combustible * as a base, it must be remembered 
that the combustible portion of a coal as fired is 100^— (per cent 
of moisture + per cent of ash). The per cent of combustible in this 
coal will then be 100- (1.5 + 5.3) =93.2j<. The percentages of C, 
H, 0, N and S in the combustible will then be 

83.5x^=89.6 C; 4.8x Jg-=5.15 H; 3.2x^ =3.35 0; 

1.2X -J^^ =1.29 N; and 0.5x i|^ =0.545 S. 

From Dulong^s formula, which is heat units = zr^ [14,600 C+ 
62,000(H-- ^ )], we get 16,015 as the calorific value per pound of 



(B) Heat Absorbed by the Boiler. — ^This must be found from an 
evaporative test of a boiler; and let us suppose that in this case the 
number of pounds of water evaporated from and at 212® F. was 
11.6 per pound of combustible. The heat absorbed by the boiler 
was then 11,257 = 11.6x970.4 (970.4 is the latent heat of steam at 
212® F.). 

(G) Loss Due to Sensible Heat in Waste Gkuies (per pound of 
combustible). — This is obtained from the analysis of the smoke- 
pipe gases and the ultimate analysis of the fuel (per pound of com- 

There are two parts of this computation: (1) The calculation 
of the number of pounds of dry gas per pound of combustible, and 
(2) the calculation of the number of pounds of steam gas per pound 
of combustible from the per cent of H in the ultimate fuel analysis 
and from the per cent of moisture per pound of combustible. 

* This is reduced to combustible as a base because the heat units are 
obtained from only the combustible constituents of the coal. 

Digitized by 


Appendix 367 

Calculation (1). — Let us assume that the analysis of the smoke- 
pipe gases gave, in per cent, 12.7 CO,, 5.7 0, 0.5 CO, and 81.1 N (by 
difference) . The per cent of N is found by taking 100 - ( GO, + CO 
+ 0). The calculations of the heat lost in the smoke-pipe gas are 
based on the supposition that the dry gas contains only GO,, GO, 
and N. The gas may contain very slight amounts of H (decom- 
posed from the moisture in the coal, probably just after firing), 
GH4, (distilled from the coal and not burned), and SO, and NO, 
(from the sulphur and nitrogen in the coal). These last four gases 
are included in the per cent of N, as they are so small in amoimt 
that they may be neglected. 

From chemistry it is learned that the weight of a gas is equal to 
its molecular weight, referred to hydrogen as unity. Each molecule 
of the gases H, and N contains two atoms ; their molecular weights 
are, therefore, twice their atomic weights. 

Atomic weights: 0=16, H=l, G=12, and N=14. The molec- 
ular weights of hydrogen and of the gases found from burning car- 
bon in air are: H=2, 0=16, N=28, CO, =12 + 32 =44, C0=12 
+ 16=28. 

In CO, carbon forms (by weight) \i, and oxygen H, or -^ and ^ 
respectively. In CO carbon forms |f , and oxygen ^, or f and f 

The weight of the dry gases will then be the percentage (foimd 
by the analysis) of each gas multiplied by its molecular weight. 

Pounds of dry gas=j<CO,x44+j<Ox32+}<COx28+j<Nx28. 
The pounds of dry gas per poimd of carbon burned will be this num- 
ber of pounds divided by the number of pounds of carbon in the gases 
containing carbon. The gases containing carbon are CO, and CO. 
The number of pounds of gases containing carbon will then be 
;^CO,x44+)^COx28, and the weight of carbon in these gases will 
then be 

as -^ of CO, and ^ of CO is carbon by weight. Letting the sym- 
bols represent the percentages by volume: 

Pounds of dry gas per pound of carbon burned 

_ 44CO, + 320 + 28CO + 28N _ 11CO,+80+7(CO+N) 
12(C0, + C0) - 3(C0,+C0) 

Dry gas per pound of carbon 

_ 11x12.7 + 8x 5.7 + 7 (0.5 + 81.1) ^.,0 1 ,, 
" 3(12T+075l ^^'^ ^^'- 

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358 Appendix 

To reduce this to dry gas per pound of combustible, we must mul- 

i.. 1 ... 89.6 

89 6 
Dry gas per pound of combustible =19.1 X^^ =17.1 lbs. 

Calctdation (2) . — In forming water, one part by weight of hydro- 
gen combines with eight parts by weight of oxygen to form nine 
parts by weight of water. Therefore the weight of H per pound of 
combustible multiplied by 9 gives the weight of water formed per 
pound of combustible when it is burned. The steam gas per pound 
of combustible from the hydrogen would therefore be .0516x9 = 
.464 lb. In addition there was 1.5;^ of moisture in the coal, and this 

forms -Q^^ ^ ^QQ =.016 lb of steam gas per pound of combustible. 

Summing up from calculations (1) and (2) : 

Dry gas per pound of combustible = 17.1 lbs. 

Steam gas from H in fuel per pound of combustible. . = .464 lb. 
Steam gas from moisture in fuel per pound of com- 
bustible = .016 lb. 

Total gas ♦ per pound of combustible 17.580 lbs. 

Suppose the temperature of the gases in the uptake to be 590** P. 
and tiiat of the external air 76** P. Por all practical purposes, and 
in view of the approximate results which can be obtained by the 
present means of gas analysis, the average specific heat of the dry 
gases may be taken as .24, and of the dry gases and steam gases com- 
bined, as .246. 

The rise in temperature of the gases is 590 — 75=515® P., and the 
product of the number of pounds of gases by the rise in temperature, 
in degrees P., by the specific heat of the gases equals the number of 
B. T. U. lost. 17.58 (lbs. of gases per lb. of combustible) x616 
(rise in temperature) X.246 (specific heat of gases) =2227.4 B. T. 
IJ. lost, the loss due to the sensible heat in the waste gases per pound 
of combustible. 

(D) Loss Due to Latent Heat in Steam Oases. — ^The loss due to 
the sensible heat has been accounted for in calculation (0). In 
addition, there is the loss of heat rendered latent in changing the 
water formed from the H and the moisture in the coal from water 
into steam. The latent heat of one pound of steam under atmos- 

* This can be reduced to pounds of gas per pound of coal or per pound 
of carbon, if desired. 

Digitized by 


Appendix 359 

pheric pressure of 14.7 pounds per square inch is 970.4 B. T. U. 
As there was .48 pound of water formed per pound of combustible 
in the above example, this loss in B. T. U. is 970.4 x. 48 =466.8. 

(E) Loss Due to Incomplete Combustion. — ^As found before^ the 
weight of the carbon in the gases containing carbon was 12 (CO, 
+ C0). The perfect, or complete, combustion of this total carbon 
would have given 12(C02+CO) x 14,600 B. T. U.= (a). But the 
combustion of the carbon, as shown by the gas analysis, was not 
complete, and the heat generated was, therefore, only 

1200^x14,600+1200x4451 ♦ B. T. U.= (b). 
The diflference between (a) and (b) will give the loss in B. T. U. 
due to incomplete combustion of carbon, or loss (a) — (b) =1200 
X 10,149 B. T. U. per pound of carbon, or, in per cent of (a) 

_ 1200^ 10J.49 X 100 _ COx 10^49 xlOO 
■" "I2(00j+C0) CO^+CO 

per lb. of carbon. Per pound of combustible this loss 
- COj<10,149 ^0 in combustible 
" 00^ + CO 100 

Substituting values from the above gas analysis, we get loss due to 
incomplete combustion, per pound of combustible, 

„ .5X10,149 89^ -3444 B T U 
~ 12.7 + .5 ^ 100 ~^^^-^ ^' ^' ^• 

(F) Loss Due to Badiation and Y>therwi8e XTnacoounted for. — This 
is taken as the difference between (A), the calorific value of one 
poimd of the combustible in B. T. U., and the sum of the values in 
(B), (0), (D) and (E) in B. T. U. 

Heat Balance. — From the above calculations the heat balance is 
made up, which shows the approximate distribution of the heating 
value of one pound of the combustible. 

Hbat Balance fbom the Analyses Given. 

Oalorific value of the combustible 16,015 B. T. TJ. 

Absorbed by the boiler 11,257 

Loss due to sensible heat in waste gases. . 2,227.4 

Loss due to latent heat in steam gases. . . 465.8 

Loss due to incomplete combustion 344.4 

Loss due to radiation and otherwise un- 
accounted for 1,720.4 

These values are frequently expressed in per cent of the calorific 
value of the combustible. 

• See Table, chapter on " Gombustion." 

Digitized by 


860 Appendix 

Tests of Coal, Proximate Analysis. 

For Hoistnre. — A portion of the sample is accurately weighed 
into an oyen and dried for 1 hour at a temperature of 105® P. The 
sample is then remoyed and.reweighed. The difference gives the 
percentage of moisture. 

For Volatile Matter. — A portion of the dry coal should be weighed 
into a flask and heated to incandescence for 15 minutes. This drives 
off the volatile combustible matter. The sample is then removed and 
reweighed; the difference^ compared with the total weight of the 
original sample^ gives the percentage of volatile matter. 

For Ash. — The remainder of the sample^ after the moisture and 
volatile matter have been driven off, is then weighed on a platinum 
dish, and then heated in the open air until all of the combustible 
matter is burned. The weight of the residue, compared with that of 
the original sample used, gives the percentage of ash. This is the 
net value of the ash, and is lower than it is possible to obtain in 
burning the coal on a grate. In practice, the ash is generally 50jt 
greater than this. 

The Fixed Carbon. — ^The fixed carbon is the difference between 
the weight of the original sample and the sum of the percentages of 
moisture, volatile matter and ash. It requires a chemist to make a 
chemical analysis of the fuel, in which the percentage of each of the 
constituents is obtained. 

Sampling. — In sampling coal for a test, the object is to obtain a 
small portion of the coal which represents as nearly as possible the 
entire lot of coal under test. Small shovelfuls of the coal should be 
taken from many parts of the pile, car or barge, care being taken to 
get about the same number of shovelfuls from the top, middle and 
bottom of the pile. The sample should contain as nearly as possible 
the same percentages of lump and fine coal as exist in the whole pile 
imder consideration. This sample is then broken up into small par- 
ticles by crushing, or with a maul, and the whole is thoroughly mixed 
into a conical pile. The pile is then quartered. Two opposite quar- 
ters are then taken, the remaining two being rejected. The two 
taken are then mixed and quartered. This process is continued 
until the lumps are \" in size or smaller, and a 1- or 2-quart sample 
remains. This sample is then hermetically sealed in glass or metal 
jars and plainly labeled. Before the jar is sealed, the identification 
record of the coal should be placed in the jar. 

Digitized by 


Appendix 361 

Fnel-Testingr Outfit. 

In obtaining the heating yalue of fuels^ both solid and liquid^ 
Mahler's fuel calorimeter is in very general use. This instrument 
is the best-known of the bomb calorimeters, in which a sample of 
the fuel under test is burned in a bomb immersed in water and the 
amoimt of the heat of combustion is measured by the rise in tempera- 
ture of the water. 

Principle, Description and Operation. — The combustible is placed 
in a closed bomb, made strong enough to resist heavy pressure and 
filled with oxygen under pressure. The bomb is immersed in the 
water of the calorimeter, and the combustion is started by an electric 
ignition device. Because of the large quantity of oxygen in the 
bomb, the combustible bums completely and almost instantaneously. 
The products of combustion are confined in the bomb, and the heat 
is given off to the water and to the various parts of the instrument. 
Such losses as occur are easily estimated, and, owing to the rapidity 
of the combustion, most of the corrections become negligible. 


Digitized by 


The apparatus is shown in Fig. 108, and consists of the following 
parts: A, water jacket; B, bomb of enameled steel; C, platinum 
tray for holding the fuel; D, the calorimeter; E, an electrode; F, a 
piece of fine iron wire for priming; 0, the support for the agitator; 
K, mechanism for agitator ; L, the leyer for operating; M, a pressure 
gage for oxygen; 0, flask of oxygen; P, an electric battery; 8, the 
agitator; T, a thermometer; and Z, a clamp for holding the bomb 
while removing or replacing the cap. 

The bomb is of the best quality of forged steely with walls 8 mm. 
in thickness and a capacity of about 650 cc. The capacity is such as 
to assure perfect combustion of the fuel by a considerable excess 
of oxygen. This bomb is used also for experiments with gas and gas 

The bomb is nickel-plated on the outside and enameled on the 
inside to protect it from attack by the nitric acid always formed 
during combustion. It is closed by a cap screwed down on a lead 
gasket. This cap has a valve in its center with a screwed nozzle 
for connecting to the oxygen flask, and is pierced by a well-insulated 
platinum electrode, which is prolonged on the inside by a platinum 
rod E, A second platinum rod, fixed to the cap, sustains the 

Digitized by 


platmuin tray C, which carries the sample of fuel under test. A 
spiral of very fine iron wire connects C with E and comes in con- 
tact with the fuel when the bomb is charged. When the current is 
turned on^ this wire is heated to redness and then bums in the at- 
mosphere of oxygen, igniting the fuel. The agitator, consisting of 
Tanes, carried on a central rod with a spiral thread passing through 
a fixed nut, is operated by a lever, which permits the operator to 
stir the water in the calorimeter systematically, thus assuring an 
even temperature. The valve on the fiask does not have a fine 
enough adjustment to permit the gradual introduction of the oxy- 
gen; hence, a second valve (not shown in the figure) having a very 
fine adjustment is placed in the connection to the tank for this 
purpose. The figure shows a fiask for oxygen, containing about 
1000 liters. It is ordinarily supplied in this manner at about 120 
atmospheres pressure. Since the pressure convenient for the com- 
bustion of one gram of coal is only about 25 atmospheres, there is 
thus a provision for about 60 tests. 

A high-grade thermometer, reading to ^® C, an electric battery 
of 12 volts and 2 amperes capacity, and a stop watch, complete the 

Digitized by 


364 Appendix 

The following method of procedure for determining the calorific 
value of a solid or liquid combustible is that given by the inventor 
of the apparatus : One gram of the fuel is weighed and placed in 
tray C. The small iron wire F, of known weight, is adjusted in 
contact with the fuel and serves as a primer. After putting the 
fuel and wire in the bomb, it is placed in the clamp Z and the cap 
is screwed on hard by means of a heavy hexagonal wrench. The 
valve on the cap is then opened, the second valve for fine adjustment 
(not shown) having first been closed. The valve on the flask is 
then opened, and then, very slowly, the adjusting valve, until the 
gage indicates 25 atmospheres. After having closed all valves, the 
tube is disconnected. 

The bomb thus prepared is placed in the calorimeter D. The 
thermometer T and agitator 8 are placed in position, and a meas- 
ured quantity of water, suflBcient to cover the bomb completely, is 
poured in. This quantity will be about 2200 cc, which is the 
amount used by M. Mahler in his experiments. The water is stirred 
for some minutes, in order to let the whole system arrive at an even 
temperature; then observations are commenced. 

The temperature is noted from minute to minute for 5 minutes, 
in order to fix the rate of variation of the thermometer before igni- 
tion. At the end of the fifth minute, contact is made and the fuel is 
fired by means of the battery connected to the electrode E and to a 
point on the valve. Ignition takes place immediately. 

The temperature is noted half a minute after contact is made, and 
then at the end of a minute; and the observations are continued 
from minute to minute up to the point where the temperature begins 
to fall regularly. This, then, is the maximum temperature. The 
observations are then continued for five more minutes, in order to 
fix the variation of the thermometer after it reaches the maximum. 
The principal data for the calculations are then at hand, including 
data for the correction for loss of heat by radiation from the cal« 
orimeter. This correction is made according to the following rules, 
true between large limits, even where the amount of contained water 
is not more than half the water equivalent of the calorimeter : 

1. The rate of decrease of temperature, observed after reaching 
the maximum, represents the loss of heat from the calorimeter 
before reaching the maximum, provided the fall in temperature is 
not greater than 1® C. per minute. 

2. If the fall in temperature per minute is greater than 1**, but 

Digitized by 


Appendix 366 

less than 2® C, the figure representing the rate of decrease, when 
diminished by 0.06, gives the desired correction. 

The two preceding paragraphs cover all cases. It is possible also, 
and that without altering the accuracy of the experiment, to con- 
sider the variation during the first half of the minute following the 
ignition as that which exists at the minimum temperature. 

During the whole of the experiment the observer should con- 
tinually operate the agitator. When the observations are ended, the 
valve on the bomb is first opened, then the bomb itself. The bomb 
will contain the ordinary products of combustion, composed princi- 
pally of carbonic acid gas and water, a considerable quantity of free 
oxygen, and an appreciable quantity of nitric acid formed during 
the combustion from such nitrogen as was present in the bomb at 
atmospheric pressure before it was charged with oxygen. 

The interior of the bomb is washed with a small quantity of water 
to remove the liquid acid formed during the combustion. The 
amount of nitric acid is then determined by a simple chemical 
analysis, and the calorific value h is determined from the formula : 

fc=r(l+a) (P+F) - (230p-f-1600p'), 

where r = the rise in temperature. 

a=the loss of temperature during the experiment. 
P= the weight of water in the calorimeter. 
P'=the water equivalent of the calorimeter. 
p= the weight of nitric acid. 
p'=the weight of the iron ignition wire. 
230= the heat of formation of 1 gram of nitric acid. 
1600= the heat of combustion of 1 gram of iron. 

In making a test of coal, no separate accoimt is taken of the quan- 
tity of sulphuric acid resulting from the oxidation of the small 
quantity of sulphur present in the sample, such acid being treated 
as nitric acid. The error is negligible in ordinary work. It may 
be noted that the sulphur being entirely oxidized and transformed 
into sulphuric acid, the bomb gives a means of evaluating it. For 
this purpose, in order to give a sufiicient quantity for satisfactory 
operation, it will be better to bum 2 grams under 30 atmospheres, 
without taking readings of the thermometer. If desired, accoimt 
may be taken of the heat generated by the formation of sulphuric 
acid, which is 0.73 calorie per gram of acid. 

In testing a substance containing but little hydrogen, coke for 

Digitized by 


866 Appbnihz 

example^ so little water of combustion is formed that the quantity 
is insnfiScient to dissolve the acid. It is then best to place in the 
bottom of the bomb a few cubic centimeters of water^ which must 
be taken into account in making the calculations. 

The procedure is the same for a liquid as for a solid. If the 
liquid gives off vapors^ it is well to weigh the sample in a closed vial 
having thin points through which is passed the film of iron wire. 
At the moment of introducing the vial into the bomb, care should 
be taken to break these points in order to bring the oxygen into 
contact with the liquid. 

This apparatus has also been used for the determination of the 
calorific value of various gases. After having exhausted the bomb 
and measured the pressure remaining, the gas is introduced for the 
first time. The bomb is then exhausted the second time, after 
which it is filled with the gas at atmospheric pressure, and at the 
temperature of the laboratory. The oxygen is then added and the 
procedure is carried on in the same manner as for solid and liquid 

The determination of the calorific value of gases offers a special 
difficulty. If diluted with too great a quantity of oxygen, the mix- 
ture will not be combustible. Five atmospheres are sufficient for 
illuminating gas and one-half an atmosphere for producer gas, 
measured on a mercurial manometer. 

Determination of the Water Equivalent of the System. — ^In order 
to determine the value of P', the term representing in water the 
exact equivalent of the system, the simplest method is to perform a 
double experiment as follows : 

Burn in the bomb a known weight, 1 gram for example, of a com- 
bustible of fixed composition, such as fuel oil, and with 2300 grams 
of water in the calorimeter. Then bum the same weight of the same 
combustible with only 2100 grams of water in the calorimeter. 
There will then be two equations between which the heat of combus- 
tion of the fuel may be eliminated and the value of the water 
equivalent may be reduced. 

Example. — ^The following example of the work of the apparatus 
is given by M. Mahler. The fuel under test is a sample of colza 
oil; an approximate analysis gave: Carbon, 77.182; hydrogen, 
11.711; oxygen and nitrogen, 11.107; weight of sample tested, 1 
gram; water in calorimeter, 2200 grams; water equivalent of the 
bomb and accessories, previously determined, 481 grams. 

Digitized by 


Appendix 367 

The apparatus being prepared, as aboye directed, a little time is 
allowed to elapse for the temperature to equalize; then the stop 
watch is started and the temperatures are noted as below. 


minutes 10.23* 

1 minute 10.23 

2 minutes 10.24 

8 minutes 10.24 

4 minutes 10.25 

6 minutes 10.26 

10.25* — 10.2S* 

U = = 0.004» 


The combustible is then fired. 

PKBIOD or Combustion. 
6H minutes 10.80* 

6 minutes 12.90 

7 minutes 13.79 

8 minutes 13.84 (max.) 

Final Pebiod. 

9 minutes 13.82* 

10 minutes 13.81 

11 minutes 13.80 

12 minutes 13.79 

13 minutes 13.78 

13.84* — 13.78* 
U = = O.OW 


No further readings of the thermometer are taken. 

The change in temperature has been 13.84** -10.25** = 3.69**. 

Corrections. — The apparatus has lost, during the minutes (7^ 8), 

(6, 7), a quantity of heat measured by 13.84**-- 13.78** x2=.024^ 
During the half minute (5^^ 6) it has lost a quantity of heat rep- 
resented by (0.012** -0.006**) X \ =0.0036**; and during the half 

minute (6, 6i) it gained i^:?^^^^^:^ X i-=.004**x |-=.002^ 

Finally, the loss during the minute (6, 6) is 0.0036** -0.002^ = 

To sum up, the loss during the whole experiment has been 
0.024** + 0.0016** =0.0266**, a quantity which should be added to the 

Digitized by 


368 Appbndix 

3.59 "* already found. The corrected rise in temperature is then 
3.615'', neglecting the tep-thonwidths. 

The quantity of heat observed is, therefore, (2200+481) x 
3.615** = 9691.8 calories. 

In order to obtain the final result, we subtract from this figure : 

1. The beat of formation of 0.13 gram of nitric acid, deter- 
mined volumetrically, 0.13x230=29.9 calories. 

2. The heat of combustion of 0.025 gram of iron wire, 0.025 x 
1600=40 calories. 

Amount to be deducted, 69.9 calories. 

The final result is then 9691.8-69.9 = 9621.9 calories, or, for a 
kilogram of oil, 9621.9 kilo-calories. 

To transform this result into B. T. U. per pound, multiply by 1.8 : 
9621.9x1.8 = 17,319.42 B. T. U. 

Applying the formula A = 14,500[C+4.28(H- ^)], we obtain 

for h the theoretical value 17,597. 

Uquid-Fuel Portable Test Outfit. 

A liquid-fuel portable test outfit that is furnished to all vessels 
that bum oil, and to all oil-supply stations, is shown in Fig. 109. 
The apparatus at the right of Pig. 109 is the Pensky-Martens flash 
tester, which is shown in detail in Pig. 110. 

This outfit has instruments for determining the flash point, per- 
centage of water and sediment, and specific gravity of liquid fuel. 
Samples are sent to the chemical laboratories at navy yards at 
Norfolk and Washington for the determination of the percentage of 
sulphur and the heating value. 

Digitized by 


Appendix 369 







Digitized by 


370 Appendix 

Pensky-Martens Hash Tester. — The Pensky-Martens apparatna 
for flash-point determination is shown in Fig. 110. 

E is the oil container, which is placed in a metal heating vessel H, 
provided with a mantle L, in order to protect H from loss of heat 
by radiation. The oil cup E is closed by a tightly fitting lid, shown 
in plan 2. Through the center of the lid passes a shaft carrying 

Fig. 110. — The Pensky-Martens Flash Tester. 

the stirring arrangement, which is worked through a flexible con- 
nection by means of the handle J. In another opening of the cover 
is fixed a thermometer. The lid is perforated with several orifices, 
which are left open or covered, as the case may be, by a sliding 
cover. This can be rotated by turning the vertical spindle with 
milled head 0. By turning 0, an opening of the slide can be. made 
to coincide with an orifice in the cover, and simultaneously a jet of 
fiame P, from a very small spirit lamp, is tilted on the surface of 
the oil. This contrivance is shown better in plan 2. 

Digitized by 


Appbndix 371 

Operation. — All water which is contained in the oil must be 
removed before testing for flash point, by filtering it through one of 
the small felt filters and funnels contained in the outfit. When the 
sample is prepared for test, the oil cup is filled up to the mark, the 
cover is fij^ed, and the oil is heated rapidly until its temperature 
reaches a point about 50^ F. below the expected flash point. The 
wire-gauze screen shown in the figure is then placed in position, and 
the rate of rise in temperature is thus reduced to about 5^ F. 
per minute. Handle J is turned slowly and continuously for stir- 
ring. From time to time the milled head Q is turned, opening the 
shutter at the top of the cup and tilting the fiame P into it. This 
is done at 5^ F. rise in temperature until near the probable fiash 
point when the intervals are made 2^ F. When the fiash point is 
reached, there will be a slight explosion when the flame is tilted 

A sample can be used for only one test, since the more volatile 
products are given off and a subsequent test would show a higher 
flash point. 

The Rre Test. — This is the temperature at which the oil will give 
off vapors which, when ignited, will bum continuously. It is made 
by continuing to heat the oil after the flash point has been deter- 
mined. In- this apparatus the cover is removed after the flash 
point has been determined ; the thermometer is left in place. When 
the fire test is completed, the fiame is extinguished by replacing the 

Test for Determining Water and Sediment. — The outfit contains 
a graduated glass cylinder, as shown in Fig.* 109, having a small 
stem at the bottom, of 3 cc. capacity. Fifty cubic centimeters of the 
oil under test is placed in the cylinder, and an equal quantity of 
gasoline or kerosene is added. The whole is then shaken thoroughly 
and allowed to stand for at least 2 hours. All of the water and sedi- 
ment will then be found to have settled in the narrow stem, where it 
can be measured. If bubbles are found to be adhering to the glass, 
they are removed with a thin wire agitator. Each cubic centimeter 
of water and sediment found in the stem will represent 2^ in the 
sample tested. 

Specific Oravity. — ^A sample of the oil is placed in the graduated 
glass jar. Fig. 109, and a hydrometer is slowly sunk into it. Care 
must be taken not to plunge the hydrometer deeper than it will 
float, as this will make an accurate reading impossible. After 

Digitized by 


372 Appendix 

reading the hydrometer^ it is removed and the temperature is taken. 
By means of a correction table, the specific gravity is reduced to 
60° F., which is the standard for comparison. 

Commercially, the specific gravity of an oil in the United States 
is usually given according to the Baimi6 scale, an arbitrary standard 
whose value at various points is as follows, the weight per gallon 
being given at 60° F. : 

10« Baumd = specific gravity 1.000 = 8.331 pounds per gaUon. 

16 " = " .967 = 8.056 

20 " = " .936 = 7.798 

26 " = " .907 = 7.556 

30 " = " .880 = 7.331 

35 " = " .854 = 7.115 

40 " = " .830 = 6.915 

45 " = " .807 = 6.723 

50 " = " .785 = 6.540 

55 " = " .765 = 6.373 

60 " = " .745 = 6.206 

Oage-Testing Apparatus. 

There are two kinds of testing outfits supplied, one of which, 
made by the Ashcroft Manufacturing Company, is shown in Fig. 
111. The cylinder in the middle is a screw pump, the plimger of 
which is worked by the hand wheel, and which is connected by a 
pipe to the two cocks at the ends of the base. A standard test gage, 
the dial of which is graduated to single pounds, is screwed onto one 
of these cocks, and the gage to be tested is screwed onto the other. 
The hand wheel being run out, the pump cylinder and connecting 
pipes are filled with water through one of the cocks, and the gage 
is then screwed into place. Pressure is now applied by screwing 
in the hand wheel, the readings of the gage for every 5 pounds 
being compared with the test gage, from zero (or from the stop 
pin, which, in high-pressure gages, is set a few pounds above zero) 
to the working pressure and back again. If the difference between 
the two gages is constant, the pointer can be removed by the lifter 
provided and be set in the correct position. A gradually increasing 
or decreasing difference may be corrected by a slight change in the 
position of the slotted lever. In a modification of this apparatus, 
che screw pump is replaced by a lever pimip. 

In the second kind of testing outfit, the pressure is produced by 
weights, and is communicated directly to the gage to be tested. No 

Digitized by 


Appendix 873 

test gage and pump are needed. There is a pipe, turned up at the 
ends, secured in a base and fitted at one end with a cock for a 
gage, similar to Fig. 111. At the other end, there is an open 
cylinder in which a snug-fitting plunger, exactly 1 square inch 
in area, can move up and down easily. The top of this plunger 

Fig. 111. — Gage-Testing Apparatus. 

is fitted with a tray on which the weights are piled, thereby in- 
creasing the pressure per square inch as desired. Glycerine is 
generally used in this apparatus, instead of water, as it lubricates 
the cylinder. While testing a gage, the plunger and its weights 
should be rotated at intervals to insure its working with the least 

Digitized by 


374 Appendix 

Draft Gage. 

Barrns Draft Oage. — The ordinary air-pressure or draft gage 
lacks sensitiveness when measuring small quantities. The BarruB 
gage, Fig. 112, multiplies the indication of the 
. ordinary U-tube by the use of two liquids of 
slightly different specific gravities, such as 
alcohol (colored red for ready observation) and 
a certain grade of petroleum oil. 

This instrument consists of a tube, usually 
made of ^" glass, which is surmounted by 
two glass chambers having a diameter of about 
2^", and arranged as shown. 

It is placed in a wooden case provided with 
a cover, and is secured in an upright position. 
Of the two liquids, which will not mix and 
which are of different colors, one occupies the 
portion A-B, and the other, which is the 
heavier, the portion B-G-D. When the right- 
hand tube is connected to the uptake or smoke- 
pipe, the suction produced by the draft draws 
Fig. 112.— Barrus the line of demarkation B downward. The 
raft Gage. amoimt of this motion is proportional to the 
difference in the areas of the two chambers of the U-tube, modified 
somewhat by the difference in the specific gravities of the liquids. 
By referring to the scale on the side, the amount of motion is meas- 
ured in inches. This scale is movable, and can be adjusted to the 
zero point by loosening the thumb-icrews. A multiplication vary- 
ing from 8 to 10 times is obtained in the instrument shown; in 
other words, with J" of draft, the movement of the line of demarka- 
tion is from 2" to 2i", the exact amount of multiplication having 
been determined by calibration referred to a standard instrument. 

Smoke Chart. 

Smoke Observations. — In order to have a uniform system of 
determining and recording the density of smoke produced, the 
smoke chart invented by Prof. Ringlemann is now used. There 
are six cards, four ruled into small squares by lines of varying 
thickness, one entirely white, and another solid black. They are 
numbered from to 5, and are hung in a horizontal row about 50 

Digitized by 


Appendix 376 

feet from the observer and, as nearly as is convenient, in line with 
the top of the smoke-pipe. At this distance, the lines on the 
ruled cards are not visible, and the cards appear to be of different 
shades of gray, ranging from very light gray to almost black. The 
observer glances from the smoke to the cards and determines which 
one is nearest in color to thit of the smoke. The number of the 
card and the time are then recorded. The observations should be 
frequent. The whole number of observations may then be plotted 
on cross-section paper, to show the variation in the smoke from 
time to time; and the average of all the records is taken as the 
average density for the test. 

The ruled cards have usually 17 horizontal and 10 vertical lines, 
spaced 10 mm. apart between centers. The thickness of the lines is 
1, 2.3, 3.7 and 5.5 mm. for cards Nos. 2, 3, 4 and 5, respectively, 
the white spaces left between the lines decreasing, therefore, from 
9 to 4.5 mm. square. 


Speoiflcations for Boiler Fittings. — ^AU external fittings on boilers 
will be composition G or Glass B cast steel, as directed. 

Each boiler will have the following fittings of approved design, 
with the necessary pipes and fittings for attaching same to boiler: 

One steam stop valve closing toward the boiler. 

One dry pipe in the steam drum or equivalent arrangement for 
insuring dry steam. 

Two main-feed stop valves and two check valves, with internal 
pipe extending nearly the full length of the drum. 

One auxiliary-feed stop valve and check valve, with internal pipe. 

One surface blow valve, with internal pipe and scimi pan. 

One or more bottom blow valves, with internal pipes, or as may 
be directed. 

One safety valve. 

One steam gage. 

Three gage cocks of U. S. Navy standard design, arranged to 
operate into the fire-room floor. 

Two water gages with automatic fittings. 

One air cock. 

One stop valve f " in diameter, for cleaning pipe connections. 

One connection for testing water. 

* Zinc protectors, with baskets for catching pieces of disintegrat- 
ing zinc. 

^ Use abandoned. 

Digitized by 


376 Appbndiz 

Polished-brass pressure and number plates^ secured to the fronts 
of the boilers and to each burner. 

Efficient and approved means for blowing soot off the tubes. 

Baffle plates and deposit pans in the steam drum. 

The number of fittings^ as specified above^ is for a boiler with a 
single steam drum. For a boiler with more than one steam drum 
the number of fittings may be correspondingly increased. 

All external fittings on boilers will be fianged and through-bolted 
or attached in other approved manner. 

All oocks^ valves and pipes, unless fitted on pads or in other ap- 
proved manner, will have spigots or nipples passing through the 
boiler plates. 

All internal pipes will be of steel, 0.083'' thick, and will not toucn 
the plates anywhere, except where they connect with their external 
fittings. The internal feed and blow pipes will be expanded in the 
holes in boiler drums to fit the nipples on their valves, or will be 
secured in other approved manner, and will be supported where 
necessary and as directed. 

The design of internal feed pipes will depend upon the type of 
boiler adopted, and will be as approved. 

All fire brick must be of standard size, attached by an approved 

Boiler Spares. — The following spare parts will be furnished and 
carried on board : 

Parts. Quantity to be furnished. 

Oil-fuel burners, complete 20 per cent 

Casing for oil-fuel burners, with doors da 

Manhole plates, with bolts, nuts, and dogs Complete for 2 boilera 

Gage cocks do. 

Water gages, complete , do. 

Water-gage glasses 100 per cent 

Mica protecting shields for water-gage glasses. . 200 per cent 

Feed check valves 2 to each hand. 

Surface blow valves 1 to each hand. 

Bottom blow valves do. 

Handhole plates, including superheater, if flt^ 

ted with bolts, nuts, and dogs 6 per cent of all. 

Special fire brick 10 per cent of all. 

Special fittings As may be directed. 

All tubes of each size and shape, including side 

and cross boxes and superheater, if fitted . . 6 per cent 
Springs for boiler safety valves Complete for 1 boiler. 

Digitized by 


Appendix 377 

Specifloations for Fuel Oil. — (a) Fuel oil shall be a hydrocarbon 
oil of best quality, free from grit, acid, and fibrous and other foreign 
matter likely to clog or injure the burners or valves. 

(b) The unit of quantity to be the barrel of 42 gallons of 231 
cubic inches at a standard temperature of 60® P. For every varia- 
tion of temperature of lO"" F. from the standard, 0.4 of 1^ shall be 
added or deducted from the measured or gaged quantity for cor- 

(c) Flash point never under 160** F. as a minimum (Abel or 
Pensky-Martens closed cup), or 175® F. (Tagliabue open cup), 
and not lower than the temperature at which the oil has a viscosity 
of 8 Engler ( water = 1 Engler). Example : If an oil has a viscosity 
of 8 Engler when heated to 186® F., then 186® F. is the minimum 
flash point at which this oil will be accepted. 

(d) Viscosity at 100®* F. not greater th^n 200 Engler. 

(e) Water and sediment not over Ifi. If in excess of 1^, the ex- 
cess to be subtracted from the volume; or the oil may be rejected. 

Hethods of Test. — (a) Flash point will be taken as indicated in 
the specifications. 

(b) Viscosity will be taken by the Engler viscosimeter: 

(c) Water and sedimejit will be taken by the distillation method. 
When oil in small lots is consigned to naval vessels or to navy yards, 
the centrifuge test will be used in order to obviate delay. In this 
test 50 cc. of oil and an equal quantity of best commercial benzol, 
50^ white, will be used, and the mixture will be heated to 100® F. 

Determination of Quantity Delivered. — (a) The officer making 
the purchase shall, when not impracticable, have an agreement with 
the agent of the company, before delivery is made, as to the method 
of determining the quantity delivered. Measurements should be 
made, when possible, by representatives of the Government and the 
contractor acting jointly. 

(b) When the oil is delivered in tank cars, where the tank cars 
are completely filled and completely discharged, the capacity to be 
taken from the gage table published under authority of the Inter- 
state Commerce Conmiission, the quantity to be corrected for 

(c) If cars are no^ completely filled or discharged, the quantity 
to be determined, if practicable, by weight at place of delivery. The 
unit of quantity to be the barrel of 42 gallons of 231 cubic inches 
at standard temperature of 60® F., the number of pounds per gallon 

Digitized by 


378 Appendix 

to be determined by the specific gravity of the oil at 60* F., multi- 
plied by 8.3316 pounds^ the weight of 1 gallon of distilled water 
at the same temperature. 

(d) If determination of weight is not possible^ the quantity is 
to be determined by the percentage of oil in the tank cars as deter- 
mined by gage to the full capacity. Unsuitable oil at the bottom of 
a tank car^ due to deposits^ will not be accepted, and will be deducted 
from the total; otherwise the cars will be completely discharged. 

(e) Where oil is delivered in barges to naval tanks, the quantity 
is to be determined by the tank's gage, allowing for capacity of lines. 

(f ) When oil is delivered in barges to naval vessels and the entire 
lot is discharged into the naval vessel, the quantities are to be deter- 
mined by the reading of the gages of the shore tanks before and after 
the loading of the barges, as ascertained by the representatives of the 
contractor and of the Government. 

(g) When oil taken from distant tanks is delivered to a naval 
vessel by barge, or the barge load is not entirely discharged into the 
vessel, the quantity is to be determined by the calibration of the 
ship's tanks, unless other method is previously agreed upon. 

Qeneral Instructions. — (a) Fuel oil for use afloat shall be re- 
quired for on requisition on the general ^storekeeper of the yard, 
and orders placed by him with the contractor in the same manner 
as for coal and other supplies. 

(b) The greatest 'care possible must be taken to determine that 
all fuel oil for use afloat shall conform in every respect to the specifi- 
cations before being taken aboard. 

(c) For the purpose of making tests aboard ship, the Bureau of 
Steam Engineering will furnish, upon application, fuel-oil testing 
outfits for determining fiash test, gravity test, cold test, and water 

(d) Arrangements for supplying fuel oil to all naval fuel-oil 
storage tanks will be made by the bureau. General storekeepers con- 
cerned will keep the bureau advised of their requirements from time 
to time. 

(e) Cau^ion.r—Vouohers for payment should be prepared by the 
officer placing the order with the contractor, except orders placed 
by the bureau, when the vouchers should be prepared by the general 
storekeeper receiving the oil. 

Digitized by 




Pbopebtier or Saturated Steam. 


in pounds 
per square 
inch, ab- 

ture of 

heat of the 


above 32* 


Total heat 

of steam, 

above 82* 


Latent heat 
of evapora- 



cubic feet 

per pound. 

pounds per 
cubic foot. 





















































































































































































8 880 





































































856 JB 











































































































































, 1208.1 





















































Digitized by 




TABLE T.— Continued. 

in pounds, 
per square 

inch, ab- 

ture of 

beat of the 


above 32" 


Total heat 

of steam, 

above 82' 


Latent heat 
of evapora- 



cubic feet 

per pound. 

pounds per 
cubic foot. 




































The pressures in this table are absolute pressures. Convert the corrected barom- 
eter reading into pounds per square Inch, add this pressure to the gase pressure, 
and with this absolute pressure enter the table for the desired data. 

Tables I and II are adapted from Marks & Davis' Steam Tables, by the kind 
permission of Professor Lionel S. Marks and Lonsmans Green & Co., publishers. 
Marks & Dayls' Tables are now considered standard Xfj the Bureau of Steam 


Absolute pres- 
sures in inch- 
es of mer- 

Absolute pres- 
s u r e 8 in 
pounds per 
square inch. 

of boiling- 
point, de- 
grees Fahr. 

Sensible heat 
of the liquid 
above 82* 


■M O 


Specific vol- 
ume, cubic 
feet per 

Density, pounds 
per cubic 

























































. 83.12 





































































































































































































































































With pressures less than atmospheric, subtract the vacuum In inches of mercury 
from the corrected barometer reading and with the remaining pressure In Inches of 
mercury enter the table for the desired results. 

Digitized by 


























































. H 












4 ■ 















Element or substance. 




air, 1. 

Weight of 

1 cubic 







































Carbon dioxide 


Carbon monoxide 


Marsh gas (methane) 


Ethy lene 




Sulphur dioxide 



* The first column of figures Is based on Hempels* Oas Analysis, and the second 
on the weight of air by Rankine, .080728 at 82* F. and at atmospheric pressure. 




Heating value of carbon burned to CO,, 14,600 B. T. U. per pound. 
Heating value of carbon burned to CO, 4,460 B. T. U. per pound. 
Specific heat of gases of combustion In either case, .24. 
Formula : Elevation of temperature in degrees Fahr.= 

B. T. U. generated by combustion 

Weight of gases X specific heat of gases 
To bum 1 pound of C to COs with no excess of air requires 11.62 pounds of air. 

making 12.62 pounds of gas. 
To bum 1 pound. of C to CO with no excess of air requires 6.76 pounds of air. 

making 6.76 pounds of gas. 


Percentage of air below 11.52 

Air per lb. of C 

Air plua G per lb. of C=lbB. o^gas 

Percentage of G burned to COs 

Percentage of G burned to GO 

Heat (B.T.U.) generated in making COg. 
Heat (B.T.U.) generated in making CO.. 

Total heat generated 

EleTation of the temperature of the fire. 
























































Percentage of air aboTe 11.52 lbs. per Ib.of C 

Lbs. of air per lb. of carbon 

Lbs. of air plus G per lb. of G » ibe. of gas 

Percentage of G burned to CO^ 

Heat (B.T.U.) generated in making COg. . . 
Eleration of the temperature of the fire. . . 

































NOTB. — ^Tke temperatures of the fire given above are theoretical and arf based on 
the assumption tbat there is no loss by radiation, convection or otherwise. Tbev 
■re never attained In practice, since the losses mentioned above are always present 

Digitized by 






Temperature Mean specific 

Substance. range in heat at constant 

degrees C. ' pressure. 

Air 20-440 .2366 

20-800 .2430 

Carbon dioxide (CO.) 15100 .2025 

11-214 .2169 

Carbon monoxide (CO) 26-19& .2426 

Hydrogen 21-100 3.4100 

Nitrogen 20-440 .2419 

Oxygen 20-440 .2240 

Sulphur dioxide (SO,) 16-202 .1544 

Water vapor 100 .421 

180 '.51 



Substance. range in Specific heat, 

degrees C. 

Alcohol .548 

(Methyl) 40 .648 

Glycerine 16-50 .576 

Oils — castor 20 .434 

Turpentine .411 

Petroleum 21-58 .511 



Substance. range in Specific heat, 

degrees C. 

Carbon— graphite 11 .16 

Copper 17 .0924 

Iron» cast 20-100 .1189 

Iron, wrought 15-100 .1162 

Lead 15 .0299 

Mercury 85 .0328 

Nickel 100 ,1128 

Digitized by 




Accessories, boilers 108 

Accessories, feed 108, 109 

Accessories, firing 109, 140 

Accessories, firing for coal burning boilers 140 

Accessories for burning liquid fuel 141 

Accessories, steam pipe 108 

Accessories, testing (Appendix) 109, 339 

Accidents, boiler 817 

Adamson's ring 28 

Air chamber 119 

Air cock 104 

Air, composition of 181 

Air extractor 124 

Air, increase over theoretical amount required 186 

Air, methods of determining the amount actually used 357 

Air, necessary for complete combustion 184 

Air pressure gages 274 

Air, quantity necessary above the grate 192 

Air registers 141, 149 

Air space 37 

Air supply 199 

Analysis, gas, deductions from 354 

Analysis of fine gases 364 

Analysis outfits, gas. 348 

Analysis outfits, Hay's 348 

Analysis outfits, Orsatt-Muencke 362 

Analysis, proximate 187 

Analysis, proximate, for ash 360 

Analysis, proximate, of coal 187, 360 

Analysis, proximate, the fixed carbon 360 

Analysis, ultimate 186 

Arrester, water 159 

Ash and clinkers 207 

Ash and soot, tools for handling 152 

Ash ejectors 152 

Ash discharger, Newport News 158, 155 

Ash hoist engine 162 

Ash hoisting 265 

Ash-pit doors 317 

Ash, treatment of 360 

Ash wets 164 


Digitized by 


384 Indbx 


Atomlzatlon, air 146 

Atomizatlon, mechanical 147 

Atomization, proper 237 

Atomization. steam 146 

Automatic control of feed pumps 116 

Automatic feed regulators 124 

Babcock and Wilcox boiler 42 

Baffle plates and drums 60-51 

Balance, heat 369 

Bars, burning of grate 37 

Bars, cooling of grate 37 

Barrus draft gage 374 

Blake simplex pump 115 

Blowers 157 

Blowers, tube 154 

Boiler accessories 108 

Boiler capacity 195 

Boiler, care and management of 301 

Boiler, care and management of, accidents 317 

Boiler, care and management of, ash-pit doors 317 

Boiler, care and management of, banked fires 316 

Boiler, care and management of, changing the water 304 

Boiler, care and management of, cleaning routine 806 

Boiler, care and management of, condition of the interior 311 

Boiler, care and management of, danger from freezing 301 

Boiler, care and management of, danger from scale and deposits. . 303 
Boiler, care and management of, draining of water containers... 311 

Boiler, care and management of, emptying 321 

Boiler, care and management of, equalization of work 311 

Boiler, care and management of, examination of tubes 306 

Boiler, care and management of, feed water heaters 315 

Boiler, care and management of, fire-room gratings 307 

Boiler, care and management of, gage tests 308 

Boiler, care and management of, general 301 

Boiler, care and management of, hauling fires 316 

Boiler, care and management of, increasing speed with fire tube. . 312 

Boiler, care and management of, loss by leakage 302 

Boiler, care and management of, low water 316 

Boiler, care and management of, periodical cleaning 306 

Boiler, care and management of, periodical overhaul 301 

Boiler, care and management ot precautions In raising steam. . . . 314 
Boiler, care and management of, precautions in regard to fuel oil, 310 
Boiler, care and management of, precautions when overhauling. . . 303 

Boiler, care and management of, preservation of idle boilers 302 

Boiler, care and management of. protection of external parts.... 307 
Boiler, care and management of, records of examinations 307 

Digitized by 


Index 385 


Boiler, care and management of, removal of impurities 304 

Boiler, care and management of, salty feed 302 

Boiler, care and management of, securing the tubes 306 

Boiler, care and management of, selection of boiler water 287 

Boiler, care and management of, steam launch, care of 311 

Boiler, care and management of, supply of feed 316 

Boiler, care and management of, test of pressure parts 308 

Boiler, care and management of, test of safety yalves 307 

Boiler, care and management of, test of water 304 

Boiler, care and management of, training of firemen 312 

Boiler, care and management of, unequal expansion 313 

Boiler, care and management of, use of bottom blow 820 

Boiler, care and management of, use of fuel oil 318 

Boiler, care and management of, water-gage fittings 308 

Boiler, care and management of, water treatment 306 

Boiler casing 64, 193 

Boiler casing, air leaks in 193, 246 

Boiler, classifications of water tube 11 

Boiler cleaning 48, 53, 63, 305 

Boiler compounds 284, 286 

Boiler, connecting to steam line 249 

Boiler, definition of 9 

Boiler design, notes on 194 

Boiler, direct fire-tube 11, 21 

Boiler, double-ended, return fire-tube, general description 14, 16, 16 

Boiler, effect of list on 103 

Boiler efficiency 194, 196 

Boiler efficiency, higher for double-ended 19 

Boiler, fire-tube 10, 14 

Boiler, fire-tube and water-tube, advantages of 13 

Boiler fittings 73 

Boiler horse-power 194, 196 

Boiler overhauling 62, 303, 306 

Boiler rating 194 

Boiler requirements 10 

Boiler, return fire-tube 10 

Boiler, routine 301 

Boiler, shell plates 22 

Boiler, single-ended, return fire-tube 19-20 

Boiler, specifications for 376 

Boiler tests 322 

Boiler tests, analysis of the gases 330 

Boiler tests, boiler and connections, the 824 

Boiler tests, calculations of efficiency 831 

Boiler tests, calorific tests and analysis of coal 329 

Boiler tests, determine at the outset 322 

Boiler tests, determine the character of the coal 323 

Digitized by 


386 Indbtk 


Boiler tests, determining the moisture in the coal 328 

Boiler tests, duration of test 324 

Boiler tests, establish correctness of apparatus 823 

Boiler tests, examine the boiler 322 

Boiler tests, heat balance, the 331 

Boiler tests, incomplete combustion 369 

Boiler tests, keeping the records 326 

Boiler tests, loss due to radiation, and unaccounted for 359 

Boiler tests, loss due to sensible heat and waste gases 366 

Boiler tests, miscellaneous 330 

Boiler tests, notice general conditions 322 

Boiler tests, quality of steam 327 

Boiler tests, report of trial 332-334 

Boiler tests, sampling the coal and determining the moisture 328 

Boiler tests, see that boiler is thoroughly heated 323 

Boiler tests, smoke observations 330 

Boiler tests, starting and stopping test, alternate method 326 

Boiler tests, starting and stopping test, standard method 326 

Boiler tests, treatment of ashes and refuse 329 

Boiler tests, uniformity of conditions 826 

Boiler, water-tube 42-64 

Boiler with accelerated circulation 12 

Boiler with forced circulation 13 

Boiler with free circulation 12 

Boiler with limited circulation 12 

Boiler zincs 106 

Boilers, Babcock and Wilcox 42 

Boilers, comparison of fire-tube and water-tube 13 

Boilers, connecting to main and auxiliary steam lines 249 

Boilers, Dyson 64-66 

Boilers, Gunboat 21 

Boilers, naval, general requirements of 195 

Boilers, Normand 67-60 

Boilers, Normand, express type, coal burning 59 

Boilers, operation of oil-burning 240-242 

Boilers, Thomycroft 60 

Boilers, Thornycroft, " Ohio " type 62-63 

Boilers, type W launch 71 

Boilers, Ward 68-71 

Boilers, White-Foster 65-67 

Boilers, Yarrow 63-65 

Boiling point 174 

Bolt, screw stay 27 

Bourdon spring gage 94 

Braces and stays 27 

Brick-work, furnace, oil-burning boilers 246 

Bridge wall 38 

Digitized by 


Index 387 


British Thermal Unit, the 167 

Brushes 155 

Buckets, coal 141 

Burners, care of 245 

Burners, oil 141, 146 

Burners, oil, Ingram 148 

Burners, oil. Bur. S. B. Standard 148 

Calculations, strength of boilers 198 

Calking tools 163 

Calorimeters, Carpenter's improved separating 842 

Calorimeters, Carpenter's throttling 840 

Calorimeters, Carpenter's throttling, calibration method 341 

Calorimeters, Carpenter's throttling, limitations of 841 

Calorimeters, Mahler's bomb 862 

Carbon 182 

Care and management of boilers (see boilers) 301 

Casing, boiler 64, 193 

Chamber, air 119 

Chamber, combustion, sheets 26 

Chemical testing outfit 292 

Chemical testing outfit, method of making determinations 295 

Chemical test, volumetric determinations 294 

Chime whistle, the 160, 161 

Circulation, accelerated 12 

Circulation, forced 13 

Circulation, free 12 

Circulation, furnace gas 46, 56, 58, 60, 64, 66 

Circulation, limited 12 

Circulation, water 45, 54, 58, 60, 64, 66, 71 

Cleaner, Weinland turbine tube 156 

Cleaning fires 264 

Cleaning, periodical 806 

Cleaning routine 306 

Cleaning tubes 106, 155 

Clinkers and ash 207 

Clothing and lagging 32 

Coal 202 

Coal, anthracite 204 

Coal, bituminous 203 

Coal, bituminous, semi- 203 

Coal, brown or lignite 203 

Coal buckets 141 

Coal, cannel 203 

Coal, calorific test and analysis of 356 

Coal, classifications of 187, 204 

Coal, combustion of. 189 

Digitized by 


388 Index 


Coal, composition of various 188 

Coal, consumption, record of 216 

Coal, determination of amount, records 212 

Coal, effect of moisture in 209 

Coal, effect of weathering on 20D 

Coal, graphitic 204 

Coal, heating value of 205 

Coal, oil as an auxiliary to 243 

Coal, patent fuel 204 

Coal, powdered 204 

Coal, precautions taken to determine amount received 212 

Coal, quality of 207 

Coal sampling 360 

Coal, specifications f or 208 

Coal, storage and spontaneous combustion 217 

Coal, storage of, under water. 209 

Coal, stowage aboard ship 210 

Coal, stowage and handling of 210 

Coal, test of, proximate analysis 360 

Coals and liquid fuel, table of compositions of 188, 206 

Coaling ship 214 

Coaling ship, at sea 217 

Cocks, air 104 

Cocks, drain 104 

Cocks, gage 96 

Cocks, gage, trying 102 

Coking system, the 26C 

Combustible substance 181 

Combustion 181 

Combustion, air necessary for complete 184 

Combustion chamber 38 

Combustion chamber girders 26 

Combustion chamber, riveting sheets 26 

Combustion, chemistry of 181 

Combustion, conditions for 268 

Combustion, heat of 183 

Combustion of coal 189 

Combustion of fuel oil 236 

Combustion, oil fuel, proper 240 

Combustion, quantity of air necessary above and below the grate. . . 192 

Combustion, rates of 262, 276 

Combustion, rates of, for forced draft 269 

Combustion, rates of, table of 263 

Combustion, spontaneous 217 

Cones, air 141, 149 

Cones, air, Schutte-Koerting 278 

Connection for testing water « 104 

Digitized by 


Index 389 


Control of feed pump, automatic 116 

Corrosion, acids, effect of 282 

Corrosion, action shown by indicators 344 

Corrosion, alloys 282 

Corrosion, boiler compounds 284 

Corrosion, cause 280 

Corrosion, effect of couples 282 

Corrosion, electrolytes 284 

Corrosion, ferroxyl mount, preparation of a simple 344, 345 

Corrosion, impure water 286 

Corrosion, indicators 294, 344 

Corrosion in distilled water 281 

Corrosion, notes in regard to solutions in general 289 

Corrosion, practical results from use of ferroxyl mount 345 

Corrosion, prevention of 291 

Corrosion, prevention of, by outside contact 291, 292 

Corrosion, reason for treating boiler water 283 

Corrosion, sea water 287 

Corrosion, sodium chloride, effect of 283 

Corrosion, test for 292 

Corrosion, theory, the acid 280 

Corrosion, theory, the electrolytic 280 

Corrosion, theory, the hydrogen peroxide 280 

Corrosion, to make water non-corrosive 283 

Corrosion, water treatment 280, 291 

Dampers 157 

Danger of liquid fuel 243 

Dewrance water-gage glass 100 

Deductions from the results of gas analysis 354 

Design, boiler, notes on 194 

Device, time firing 141 

Devil's claw 140 

Dogs 43 

Doors, ash pit 317 

Doors, furnace 39, 40 

Doors, furnace, modern 41 

Double acting pump / 114 

Draft, forced 269 

Draft, forced, closed ash-pit system 269 

Draft, forced, closed fire-room system 274 

Draft, forced, for liquid fuel 240, 277 

Draft, forced, Howden's system 271 

Draft, forced, induced 273 

Draft, forced, induced, Ellis and Evans' system 273 

Draft, forced. Koerting patent for oil-firing system 278 

Digitized by 


390 Index 


Draft, forced, rate of combustioii 276 

Draft, forced, steam jet 269 

Draft, llmlUtlons of 268 

Draft, natural and forced 267 

Draft, natural, calculations for 267 

Draft, natural (smoke pipe) 267 

Draft, pressure drop 276 

Draft, pressure drop, effects of 277 

Draft, significance of 276 

Drain cocks .- 104 

Drums, steam 61 

Dry pipes 78 

Dudgeon tube expander Ib5 

Dulong's formula 184 

Duplex oil service pump 144 

Dyson boiler 54-56 

Efficiency, boiler 194, 195 

Efficiency, calculation of 331 

Efficiency, furnace 191 

Sufficiency of heating surface 195 

Ejectors, ash 162 

Elliott strainer 146 

Ellis and Evans' system of forced draft 273 

Engine, ash hoist 162 

Engines, warming up * 260 

Equivalent, Joule's 167 

Escape pipes 140 

Evaporation, actual and equivalent Iv9 

Evaporation, factor of 180 

Evaporation, power of fuel 179 

Evaporation, unit 179 

Expander, tube 165 

Expansion Joints 126 

Expansion steam traps 183 

Expansion, unequal 313 

Extractor, grease 119 

Extractor, air 124 

Fan, Sirocco, with Terry steam turbine 158 

Feed 109 

Feed accessories 109 

Feed and filter tanks 110 

Feed discharge Ill 

Feed piping, size of 199 

Feed pumps 118 

Feed regulator ^ 124 

Digitized by 


Indbx 391 


Feed, salty 820 

Feed, supply of 316 

Feed suction pipes Ill 

Feed system, to prevent salt from entering 302 

Feed tanks, reserve Ill 

Feed water 109, 110 

Feed water heaters 120 

Feed water heaters, coil 121 

Feed water heaters, film 121 

Feed water heaters, Schutte-Koerting 122 

Feed water heaters, ReiUy multicoil 128 

Feed water heaters, straight flow 121 

Feed water heaters, U-tube 122 

Ferrules 30 

Film oil heater 145 

Filter tanks 110 

Fire test 371 

Fires, banked 315 

Fires, hauling 316 

Firemen, training of 312 

Firing 247 

Firing accessories 109, 140 

Firing accessories for coal burning boiler 140 

Firing accessories for liquid fuel burning boilers 141 

Firing, alternate front and back system 257 

Firing, alternate side system 256 

Firing, bad 267 

Firing, cleaning fires *. 264 

Firing, coking system, the 255 

Firing, connecting boilers to main and auxiliary steam lines 249 

Firing, controlling the steam 251 

Firing, even-spread 254 

Firing, fuel oil 240 

Firing, fuel oil as an auxiliary to coal 243 

Firing, fuel oil, atomizing the oil 238 

Firing, fuel oil, combustion of 239 

Firing, fuel oil, comparative value of oil and coal for naval use. . . . 236 

Firing, fiiel oil, danger of system 243 

Firing, fuel oil, lighting fires 242 

Firing, fuel oil, quantity and velocity of air 239 

Firing, fuel oil, rapidity of getting the fuel on board 235 

Firing, fuel oil, reduction in fire-room force 235 

Firing, fuel oil, steaming radius 235 

Firing, fuel oil, stowage 236 

Filing, fuel oil, with no steam on ship 241 

Firing, fuel oil, with steam already on boiler 242 

Firing, good 268 

Digitized by 




Firing, hand 262 

Firing, hoisting ashes 266 

Firing, intelligent, supervision of 269 

Firing, methods of, with coal 261 

Firing, no particular system adopted in the Navy 267 

Firing, pointers on 259 

Firing, precautions prior to lighting 247 

Firing, , priming furnaces 248 

Firing, rates of combustion •. 262 

Firing, starting and getting up steam in coal-burning boiler 248 

Fittings, boiler 73 

Fittings, specifications for 375 

Fittings, water gage 101, 308 

Flame 240 

Flash point 225 

Flash tester 870 

Forced draft 269 

Forced draft, Howden's system 271 

Formula, Dulong's 184 

Foster pressure regulator 136 

Fox's corrugated furnace 28 

Freezing, damage from 301 

Fronts, furnace 39-40 

Fuel, chemistry of 181 

Fuel, composition of 181 

Fuel, liquid 220 

Fuel, liquid, advantages of 236 

Fuel, liquid, classes of : 220 

Fuel, liquid, comparison of the value of with coal 230 

Fuel, liquid, composition of 223 

Fuel, liquid, critical point 226 

Fuel, liquid, dangers of 243 

Fuel, liquid, disadvantages of 236 

Fuel, liquid, fire point 226 

Fuel, liquid, flash point 225 

Fuel, liquid, for battleships 148 

Fuel, liquid, petroleum, properties of 221 

E\iel, liquid, physical characteristics of 223 

Fuel, liquid, portable test outfit 368 

Fuel, liquid, storage and transportation of 226 

Fuel, liquid, supply of oil fuel 220 

Fuel, liquid, temperature viscosity curves 225 

Fuel, liquid, viscosity 224 

Fuel oil piping 141-142 

Fuel oil, specifications for 377 

Digitized by 


Iin>EX 393 


Fael oil storage tanks 141-142 

B\iel. patent 204 

Furnace 27 

Furnace, Adamson's ring 28 

Furnace doors 39, 40 

Furnace efficiency 191 

Furnace, Fox's corrugated 28 

Furnace fronts 39» 40 

Furnace. Morrison's suspension 28, 29 

Furnace, Purves 28 

Furnace sheet 24 

Furnace temperatures 190 

Furnaces, priming 248 

Gage, Barrus draft 874 

Gage, Bourdon spring 94 

Gage cocks 96 

Gage glass. Star 98 

Gage glasses and cocks, trying 96 

Gage testing apparatus 372 

Gage tests 308 

Gages, air pressure 274 

Gages, steam 94 

Gages, water, location of 101 

Gas analysis apparatus. Hay's 348-361 

Gas analysis apparatus, Orsatt-Muencke 362» 863 

Gas analysis, deductions from results of 259, 351» 354 

Gas analysis, notes and precautions in regard to 352 

Gas analysis outfits 348 

Gas, calculations from results of 355 

Gas, furnace circulation 46, 56, 58, 60, 64, 66 

Gas passages 199 

Gases, analysis of flue 354 

Gases, loss due to heat of 356 

Gases, loss due to incomplete combustion 359 

Gases, loss due to latent heat in water 358 

Gaskets and Joints, manhole 34 

Gate valves 112 

Glass, Dewrance water-gage 100 

Glasses, water-gage .....: 98 

Girders for bracing top or curved sheets 26 

Girders for bracing top of flat combustion chamber 26 

Girders for tying two back combustion-chiunber sheets 26 

Grate bars 34-36 

Grate surface 198 

Digitized by 


394 Index 


Grates 34-36 

Gratings, fire room 307 

Grease extractor 119 

Handholes 83 

Hand pump 141, 144 

Hay's gas analysis apparatus 348-351 

Head sheets 24 

Head sheets, flanging to shell 26 

Head sheets, method of flanging 26 

Head sheets, riveting 26 

Headers 61 

Heads, steam drum 49 

Heat 166 

Heat balance 369 

Heat conduction 172 

Heat convection 172 

Heat, energy of 166 

Heat, examples 167 

Heat, latent 176 

Heat losses in boiler 366 

Heat, mechanical equivalent of 167 

Heat of combustion 184 

Heat of vaporization, total 177 

Heat, quantity of 177 

Heat radiation 171 

Heat required to produce steam when feed water is at a tem- 
perature other than 32** F 179 

Heat, sensible 176 

Heat, speciflc and thermal capacity 168 

Heat, temperature or sensible 167 

Heat, total, of wet steam 178 

Heat transfer 171 

Heat transfer and evaporation 166 

Heat, transmission of, into heating surfaces 173 

Heat, unit of , 167 

Heat, variation of speciflc of water 168 

Heaters, feed water 120 

Heaters, feed water, coil 123 

Heaters, feed water, film 121 

Heaters, feed water, Reilly multicoil : 123 

Heaters, feed water, Schutte-Koerting 122 

Heaters, feed water, straight flow 121 

Heaters, feed water, U-tube 122 

Heating surfaces 9, 198 

Heating surfaces, efficiency of 174 

Heating value of compound of mixed fuels 184 

Digitized by 


Indbz 395 


Heating values of pure substances burned in oxygen 183 

Howden's system of forced draft 271 

Hydrogen 182 

Hydrometer, principle utilized 104-105 

Indicators 294, 344 

Impurities* removal of 304 

Inside-packed-plunger pump 114 

Internal feed pipes 85 

Joints, expansion 126 

Joule's equivalent 167 

Kiely and Mueller steam trap 132 

Kinney pump 232 

Koerting patent oil firing system for boilers on torpedo-boat de- 
stroyers 278 

Liagging and clothing 32 

Lazy bar 140 

Leakage, loss by 302 

Le Chatelier's pyrometer 346 

Leslie reducing valve 138 

Lignite 203 

Liquid fuel (see fuel) 220 

Liquid fuel, accessories for burning 141 

Liquid fuel, portable test outfit for 368 

Loss by heat of gases 356-358 

Loss due to incomplete combustion 339 

Loss due to latent heat in H,0 358 

Low water 316 

Lytton bucket steam trap 130 

Lytton reducing valve 134 

Mahler's bomb calorimeter 362 

Management and care of boilers 301 

Manholes 33 

Manholes, gaskets and Joints 34 

Materials 200 

Miscellaneous accessories 108, 159 

Moisture, determination of, in coal .187, 360 

Natural draft 267 

Natural-forced draft register. Bureau Engineering 151 

Nitrogen 182 

Normal solution 289 

Normand boiler 57-60 

Normand boiler, express type, coal burning 59 

Digitized by 


396 Index 


Oil as an auxiliary to coal 242 

Oil burners 141, 146 

Oils, classes of 220 

Oil fuel (see fuel) 220 

Oil fuel, proper burning of 237-242 

Oil fuel for battleships 148 

Oil fueU precautions in regard to 310 

Oil heater, pressure, location of 141, 144 

Oil heater, Schutte-Koerting, film 145 

Oil, specific gravity ^ . . . . 871 

Oil strainers 146 

Oil, use of fuel , 818 

Orsatt-Mnencke gas analysis apparatus 3^2 

Outside-packed-plunger pump 116 

Overhauling 52, 303, 305 

Oxygen 182 

Parts, spare 376 

Passages 199 

Patent fuel 204 

Peabody impeller plates 149-160 

Peat 202 

Pensky-Martens' flash tester 370 

Petroleum, properties of 221 

Pipe lines, liquid fuel 227 

Pipes, dry 78 

Pipes, escape 140 

Pipes, feed discharge Ill 

Pipes, feed, size of 126 

Pipes, feed, suction Ill 

Pipes, internal feed 86 

Pipes, main steam, size of : % . 198 

Pipes, method of fitting internal blow to valve 87 

Pipes, passing through water-tight bulkheads 127 

Pipes, smoke 39 

Pipes, stand 101 

Pipes, steam, accessories 108 

Pipes, steam, size of 198 

Piping, steam and accessories^ 126 

Plans, tentative, for boiler construction 198 

Plates, swash 107 

Plugs for tube-removing holes 66 

Pneumercator, the 228 

Pointers on firing 269 

Pot, sallnometer 104-106 

Power, evaporative, of the fuel 179 

Precaution in regard to fuel oil 310 

Digitized by 


IKDBX 397 


PrecauMons in raising steam 3X4 

Preservation of idle boilers 302 

Pressure gage, air 374 

Pressure parts, tests of 308 

Pressure, steam, limits of 13 

Prevention of corrosion 291 

Prickers 140 

Proximate analysis of coal 205 

Pump governor, the Ideal 118 

Pumps, automatic control of feed 116 

Pumps, booster 141-143 

Pumps, double-acting 114 

Pumps, duplex oil service 141, 144 

Pumps, feed 113 

Pumps, hand 141, 144 

Pumps, inside-packed-plunger 114 

Pumps, outside-packed-plunger 115 

Pumps, piston 113 

Pumps, turbine, the 115 

Pumps, turbine, the Worthington 115 

Pyrometers 346 

Pyrometers, cajorimetric 846 

Pyrometers, expansion 346 

Pyrometers, gas 346 

Pyrometers, Le Chatelier's 346 

Pyrometers, mercurial 846 

Pyrometers, pneumatic 846 

Pyrometers, reflecting 346 

Pyrometers, resistance 346 

Pyrometers, thermo-electric 346 

Quimby screw pump 231 

Radius, steaming 235 

Rating, boiler 194 

Records of coal consumption 216 

Reducing valve, the Lytton '. 134 

Register, air 141, 151 

Regulator, automatic feed 124 

Report of boiler trial 332>S34 

Reserve feed tanks Ill 

Ring, Adamson's 28 

Ring, stiffening 28 

Riveting combustion-chamber 25 

Riveting head sheets 25 

Riveting, methods of 23 

Riveting sheets 24 

Digitized by 


398 Indbz 


Salinometer pots .104-105 

Scale and deposits, dangers from ; 303 

Scale, removing tools 155 

Schutte-Koerting feed water heater 122 

Schutte-Koerting film oil heater 145 

Seam, double butt strap, longitudinal 22 

Separators 128 

Separators, Stratton, the 129 

Setting losses 195 

Settling tanks 142 

Sheets, furnace 24 

Sheets, head 24 

Sheets, tube 24 

Shrieking whisUe 161 

Siren 162, 163 

Sirocco fan, with Terry steam turbine 158 

Slice bars '. 140 

Smoke 189, 240 

Smoke observations 874 

Smoke pipe 39 

Solution, normal 289 

Solution, notes in regard to, in general 289 

Solution tension 285 

Space, air 87 

Space, fireroom 200 

Spaces, steam 200 

Spare parts 376 

Specific gravity 871 

Specifications for boiler fittings 87( 

Specifications, boiler spares 376 

Specifications for coal 208 

Specifications, fuel oil 377 

Speed increasing with fire-tube boilers 812 

Spontaneous combustion of coal 217 

Stand pipe lOJ 

Star gage glass 98 

Stay bolt, screw 27 

Stays and braces 27 

Steam, controlling the 251 

Steam, formation of 174 

Steam, formation of, under constant volume ^ 174 

Steam gage 94 

Steam, getting up 248 

Steam, heat required to produce when feed water is at a temperature 
other than 32« F 179 

Digitized by 


Index 399 


Steam, heat, total of wet 178 

Steam launch boiler, care of 301, 311 

Steam piping and accessories 198 

Steam, precautions in raising 314 

Steam, saturated 177 

Steam spaces 200 

Steam, superheated 178 

Steam traps 130 

Steam, wet 178 

Steaming radius 235 

Stokers, mechanical 251 

Stopper, tube 31 

Storage and transportation of liquid fuel, notes on 226 

Stowage and handling of coal 210 

Stowage of coal al)oard ship 210 

Strainers 141 

Strainers, Elliott 146 

Strength, calculations for boilers 198 

Suction, feed tanks Ill 

Sulphur 182 

Superheaters 49 

Surface, heating 9, 198 

Suspension furnaces 28-29 

Swash plates 107 

Systems of firing (see firing) 264 

Table of densities 381 

Table of composition of coals and liquid fuels 188, 206 

Table of temperatures of the fire when burning pure carbon with 

varying amounts of air 381 

Table of specific heats 382 

Table, oxygen and air required for the combustion of carbon, 

hydrogen, etc. 381 

Table of properties of saturated steam 379 

Tanks, feed and filter 110 

Tanks, filter 110 

Tanks for liquid fuel 142 

Tanks, reserve feed Ill 

T-casting for steam distribution 80 

Temperatures, furnace 190 

Temperatures of the fine gas for draft 268 

Tension, solution 285 

Test apparatus, gage 372 

Test, the fire 371 

Test to determine water and sediment in oils 371 

Testing accessories (Appendix) 339 

Digitized by 


400 Index 


Testing outfit, chemical (see chemical testing outfit) 292 

Testing outfit, fuel, Mahler's. , 362, 863 

Testing outfit for liquid fuel 368 

Tests, boiler (see boilers) 304 

Tests, flash, Pensky-Martens', the 870 

Tests, gage 372 

Tests of pressure parts 308 

Thermal energy 166 

Thermometers 846 

Thermometers and pyrometers 346 

Thermometers, stem correction 346 

Thomycroft boiler 60 

Thomycroft boiler, " Ohio " type • 62-63 

Throttle valve, automatic control for feed pumps 116 

Tim« firing device 141 

Tools 63 

Tools, calking 163 

Tools for handling ashes and soot 152 

Tools, scale removing 155 

Training of firemen 312 

Traps, steam 130 

Traps, steam, expansion 133 

Traps, steam, intermittent 180 

Traps, steam, Lytton bucket 130 

Tube blowers 154 

Tube brushes 165 

Tube expander. Dudgeon 166 

Tube, Field, the 68 

Tube stopper 31 

Tubes 39 

Tubes, above water 12 

Tubes, cleaning 106, 155 

Tubes, drowned 12 

Tubes, examination of 306 

Tubes, ordinary 29 

Tubes, renewal 306 

Tubes, renewing defective 53 

Tubes, securing 306 

Tubes, stay 29-30 

Tubes, water, size of 11 

Turbine pump 115 

Unit, British Thermal, the 167 

Unit, evaporative 179 

Uptake 89 

Digitized by 


Inobx 401 


Valence 289 

Valve, auxiliary check 82 

Valve, bottom blow 8<^88 

Valve, combined feed stop and check 82 

Valve, feed check for steamers ; 86 

Valve, gate 112 

Valve, load on safety 807 

Valve, main check 82 

Valve, method of fitting internal blow pipe to 87 

Valve, ordinary stop 76 

Valve, reducing 183 

Valve, reducing, the Lirtton 134 

Valve, safety 88 

Valve, safety, care and oyerhaoling of 93 

Valve, safety, gag 92 

Valve, safety, lift of 91 

Valve, safety, lifting gear 92 

Valve, safety, resetting 92 

Valve, safety, springs 89 

Valve, safety, test of 93 

Valve, seatless bottom blow 87 

Valve, self-closing stop 76 

Valve, surface blow 87 

Valve, throttle, automatic, regulating for feed pumps 116 

Valve, with by-pass 78 

Viscosity 224 

Volumetric determinations 294 

Wall, bridge 38 

Ward boiler 68 

Water and sediment, test for determining, in oils 371 

Water arrester 169 

Water, changing the 304 

Water circulation 45, 54, 58, 60, 64, 66, 71 

Water, connections for testing 104-106 

Wator, feed 109-110 

Water, feed, salty 302 

Water, feed, supply of 316 

Water-gage fittings 308 

Water-gage glasses 98 

Water-gage glasses, Dewrance 100 

Water gage, location of 101 

Water heaters, feed 120 

Water heaters, feed, coll 123 

Water heaters, feed, film 121 

Water heaters, feed, Reilly multicoll 123 

Water heaters, feed, Schntte-Koerting 122 

Digitized by 


i02 Indbx 


Water heaters, feed» straight flow 121 

Water heaters, feed, U-tubes 128 

Water, impure 286 

Water, low 316 

Water rate 197 

Water, salt, to prevent from entering feed tanks 802 

Water, sea 288 

Water, selection of boiler 287 

Water, test of 296 

Water treatment 291 

Water, to make non-corrosive 283 

Water-tube boilers 42-64 

Warming up the engines 260 

Weinland turbine tube cleaner 166 

Wets, ash , . . . . 154 

Whistle and siren 159, 160 

Whistle chime 160, 161 

Whistle, shrieking 161 

Whistle, the BeU 161 

White-Porster boiler 65-67 

Yarrow boiler 63-66 

Zincs, boiler 106 

Zincs, use of 282 

Digitized by 


Digitized by 





This book is due on the last date stamped below, or 

on the date to which renewed. 

Renewed books are subject to immediate recalL 





APR? 9 1956 HH 


J0^«^ »'"' 


LD 21-100m-2,'55 

General Library 

University of California 


Digitized by 


YC 53886 

f • r '\. 



■ * T- : 

Digitized by 


Digitized by